Making decisions is important, and it can be difficult.
You might hear them say: IT' UP TO YOU !
To find out what This one mean, let's listen to this conversation.
What do you want?
It's up to you.
Whatever you want, we'll have.
When you say, "it's up to you", it's another way to say that you want the other person to choose.
That might be because you can't decide, or you are being nice and are letting someone else choose It's up to you!