"Use" in law means how someone is allowed to interact with something. Think of a rule book that tells you how to play a game. The rule book says what moves you can make and what you can't. In law, "use" is like the rule book for how you can treat something.
For example, if you own a piece of land, there might be rules about how you can use it. You might be allowed to build a house on it, but not a factory. You might be allowed to grow crops on it, but not store hazardous waste.
"Use" can also apply to things like software, music, or images. When you buy a song on iTunes, for example, the "use" rules might say that you can listen to it on any device you personally own, but you can't share it with others or use it in a public performance without permission.
Overall, "use" is the set of rules that explain what you're allowed to do with something you own or have permission to use. It's like the manual that tells you how to play by the rules.