The expression, “the ball’s in (your) court,” is typically used to express that it is now the other person’s turn to commit to the next move. This expression comes from the game of tennis, where it is now the opponent’s turn to perform the next action. This is usually a follow-up expression where the first person had already initiated the first action and it is now the other person's turn to react to it.
“The salesman provided the customer with all of the information and details about the product and also offered him a great discount as well. The ball is now in the customer’s court to decide if he wants to buy it or not.”
Mary: “My boyfriend and I have been together for about 10 years now and I think I’m ready to take it to the next level. We both have good jobs now and we both still love each other very much.”
Lisa: “Have you tried asking him if he wants to start a family together?”
Mary: “I did and he said he needed a bit more time to think about it.”
Lisa: “Okay, then it sounds like the ball is in his court now.”