也许你该告诉我，这到底是怎么一回事。

Maybe you'd better tell me what this is all about.

《柯林斯英汉双解大词典》

你只要在一个炎夏的日子到城里走一走，就会知道这是怎么一回事。

Go around the city on a hot summer day to get an idea of how this works.

youdao

所谓长大，就是你知道那是怎么一回事；所谓成熟，就是你知道后故意说不知道。

Growing-up means you know what and how it is, while mature means you don't speak it out on purpose after knowing the nature.

youdao