My uncle got diagnosed with stage IV bladder cancer and we just found out about it. He didn't want anyone to know because he doesn't have a lot of time left. I am going to visit him in a fews days and... I don't know what to do. I know for a fact that I am going there to say goodbye but... I don't know how I am going to spend my time with him. It's just that, he can't walk, he can barely talk, and he wants to be alone. I love my uncle, I truly do but I don't want to make him uncomfortable. I just want to spend time with him like we usually do (going out to eat, shopping for random cool things. etc) but he can't really do any of that at the moment. Really, I just want to make him happy and make sure that we do not regret anything. I know people are going to say "do things that he wants to do" but arrrgggghh this is just so frustrating. Death in the family is hard. I don't want him to go. What should I do?

Just talk to him. Even if he can't respond very well, it's still very comforting. If his motor and cognitive skills are still ok, you can play a board game.
I recently visited my friend's ill grandmother with her, and we basically just talked to her about everything. Granted, she was in a nursing home and didn't have much else to do, but the point is that good mood, attitude, care, and conversation are all things you can never go wrong with.