It's similar to the English phrase "what will be, will be," but with a stronger emphasis on resignation and acceptance. It suggests that you can't control everything and that you should just accept what happens, rather than trying to fight against it.
Here are some examples of how "que serra" can be used:
* "Não adianta se preocupar, que serra." (It's no use worrying, what will be, will be.)
* "Ele vai fazer o que quiser, que serra." (He will do what he wants, come what may.)
* "Vamos tentar o nosso melhor, que serra." (We will try our best, what will be, will be.)
Note: "Que serra" is a common phrase in Portuguese, but it's not used as often in other languages. It's a good phrase to know if you're learning Portuguese or if you're dealing with someone who speaks Portuguese.