While we often try to identify single individuals who invented things, most things are invented by a combination of people. The light bulb is no different. The light bulb was not invented all at once by a single person. Instead, many different people contributed to the development of light bulbs. However, if you are required to identify one person as the inventor of the light bulb, the answer you are expected to give is almost certainly Thomas Edison.
Edison was not the first person to come up with the idea of an electric light bulb. He was not even the first person to make a light bulb that worked. Instead, he was the first person to come up with (of course, the other people who worked for him in his labs helped) a light bulb that lasted long enough to be really useful. This is why we tend to identify Edison as the inventor of the light bulb.
You can follow the links below for a more in-depth discussion of the development of the light bulb. The links show the names of other people who helped in that development. However, Edison is still the most likely answer to your question.