Something that is adjusted is altered or fixed slightly to better go with the needs of what's around it. When you move to a new place, it takes a little while to get adjusted or used to the new environment.
If you lose weight you might have to get your pants adjusted or altered slightly to fit and look better. If you have a well-adjusted personality, you are someone who can get adjusted or situated to a particular set of circumstances easily and without much fuss. As you can see, the meaning of the word can be adjusted or altered slightly, depending on what context it's used in.