It doesn't make any sense...

Do you guys know what that means? It means that something isn't logical. It seems crazy to you and you can't understand it.

To make sense

To be logical, reasonable and understandable..

His explanations always make perfect sense.

What you're saying makes sense.

I can't make sense of calculus. It is too hard!

That movie didn't make any sense, I don't get why he wanted to date Julie... she was pretty but her character was so mean!

To not get something means to not understand something.

As you can see it is often used in a negative form to say that you didn't understand something or something isn't logical. You can also use it in a even more casual way by saying:

To make no sense

He was talking but what he was saying made no sense!

I could make no sense of what was written because of your horrible handwriting.(sounds formal)

It makes no sense coming back here tomorrow, let's just buy it now.

You can also have sense. In this case, it means that you are a reasonable person who makes good decisions.

He has a great fashion sense.
He is fashionable.

He has no sense.
He is foolish.

In British English, you will often hear the word nonsense. This sounds quite formal and means something is wrong, foolish or in vulgar North American English bullshit. 

Alice: Someday, Man will walk on Mars.

David: That's nonsense, it is too expensive. Man will never go there!

 Any questions?

Phil