This is a big question, and I am not sure what context it is being asked in. But even if you live in a cave all by yourself, it is impossible not to interact with your environment!
Your environment is everything outside your body, really, and interaction with your environment is a question of what goes in or does not go in and how you respond. You have five senses, sight, hearing, touch, smell, and taste. Those are the only ways you get input from your environment. You can choose to block out some of what is external to you, for example, when some young people play video games and do not hear their mothers calling them for dinner. Or you can choose to be open with all five senses to the environment around you, as we sometimes do when we are relaxed on a vacation and deeply appreciate all the sights, sounds, textures, smells, and tastes in our environment. Either way, it is fair to say that we are interacting with the environment, through blocking parts of it or being open to all of it.
What you do with the input is going to be a way of interacting with your environment. If you see someone smile at you, you are likely to interact by smiling back. If you taste a food you like, you are likely to eat more of it. If you smell something unpleasant, you are going to move away, and if you touch something slimy, like a ray, you are not likely to want to touch it again. If you hear music you like, you may turn it up louder or play that tune again. In this way, humans are not all that different from amoebas. We move toward what is good and away from what is bad.
In terms of interaction in particular contexts, for instance, school or work, the major difference is that there are social expectations for our interactions. We must often conceal a distaste for something or someone who is unpleasant, and we are often called upon to not move away. If a teacher whom you do not like calls upon you, you are expected to interact in a prescribed way, just as you are expected to interact in a prescribed way if a boss you do not like calls you into the office.
I hope this discussion of interaction with the environment is helpful to you, and certainly, if there is a particular context you want some discussion on, just let us know.