I wish he would make up his mind and could make it. Can someone explain the meanings of "make" in this sentence?

There are many, many, many idiomatic uses of the word "make".

to make up = to organize
to make up one's mind = to decide (to organize one's mind?)
to make it = to come

There are other meanings for make up and make it, but they don't relate to your question.
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Could you give us an example/s where the three above-mentioned were used? Thanks.
OK. Your example works. Here are three more off the top of my head.

Please hang this card on your doorknob if you would like the maid to make up your room. (in a hotel)

The boss finally made up his mind. We're all getting raises.

My wife just called, I can't make it to the pub after work.