Development of various technologies affect people and the environment in a lot of way. For instance, in the biomedical field (biosciences), the development of drugs require testing on animals and humans before they are considered viable treatment options. In biotechnology, companies might need to expand and take up land, necessitating deforestation to acquire more lot for expansion. These simple considerations all deal with ethics. Biomedical scientists cannot just give an untested drug to a person to see what happens, or lie to the person about possible side effects. Land cannot just be bought regardless of its effect on the environment or communities for a laboratory to be expanded.
Ethics consists of a set of values and beliefs long believed and accepted by a culture or in the case of some universally accepted by most of the world's population - for example, murder is not acceptable. Obviously, science is not immune to any ethical questions such as whether murder is acceptable, but in the biosciences, ethics usually deals with testing technologies and drugs on humans.
A more recent issue would be the CRISPR/Cas9 system. The system was discovered and developed to be a highly efficient genome editing tool. Ideally, as long as the sequence is known, any sequence of DNA can be edited and any mutation can be introduced. In an ideal world, this is perfect. This means that genetic diseases can now be cured by simply utilizing the technology. However, the system is not perfectly studied yet, and off-site effects are not yet completely documented. Without ethics standing in the way, a scientist could use this system without any further test say on an embryo predicted to have an illness - or maybe even introduce a very rare illness - to see if it works. You can even get an adult, introduce an engineered CRISPR/Cas9 that will change the color of his eyes. However, that is not the case. This is not considered ethical - or at the very least, is considered a grey area in the field. Not fully understanding yet the consequences of the technique makes it very iffy to try on a human subject.
The same is the case for novel treatment procedures. In the instance that a scientist notices that formulation A kills a certain form of bacteria similar to one that infects humans, he cannot simply jump ahead and give formulation A to everyone with that infection. He has to study it, elucidate it's properties, cross-reaction with other drugs, and then go through the different phases of clinical trials - and each of those clinical trials are tightly regulated by an ethics board to ensure that fabrication of data isn't done (this is another ethical concern in the sciences, but not one that is related to limiting the natural sciences).
In all these cases, ethics is limiting the progress of science in a way that it slows it down. Testing the CRISPR technology straight to humans will directly reveal the effects it has on humans, if any. However, questions like 'which humans do we use as guinea pigs?' or 'what if the test subject dies?' arise and this is where ethics comes in.
The natural sciences allow human technology to progress - to make life easier, and to cure diseases. While it can be argued that the existence of rules based on ethics - norms and beliefs of a culture - can hinder and slow down the process of discovery, it can also be argued that ignoring these rules will be counterproductive as you will be, in a sense, sacrificing a few (although in a utilitarian sense, the good of the many is still the priority).
The ethical concerns and issues in science are very complicated. Some scientists may have the tendency to skirt these ethical regulations because their priority is discovery (again, fabrication of data and making up stuff is not what I'm talking about here, but tests that would otherwise seem be considered unethical due to involvement of human test subjects). This is why in every funding agency and research regulatory boards, an ethical committee exists - to ensure than everything is done according to universal ethical principles.
To end this, I'd like to talk about Barry Marshall. He was studying H. pylori and suggested that it causes ulcers. No one in the scientific community believed that a bacteria can survive in the extreme environment in stomach acids (no proof then, so it wasn't their fault). Marshall thought it was possible, and so ingested the bacteria - after a few days, he got ulcer and proved it was caused by a bacterial agent. He goes on to win the nobel prize for this discovery. This was not an ethical move by today's standards. However, had he not done that, it might have taken a few years to understand the disease.
In the end, we see that there is a complicated relationship between ethics and scientific discovery - particularly the speed by which discoveries are made (another example is during the dark ages, when religion blocked scientific discovery, while different it is an example of the effect of a wide-spread norm). However, it should be kept in mind that the sciences work for the betterment of the world, and as humans, we all subscribe to some universal ethical 'law,' and since science is a human endeavor, it might sometimes be necessary for it to abide by these too - otherwise, it might lead to chaos.