He says the shirt is too form fitting.

他说这件衬衫太合身了。

The sleeves were too short and it was too form fitting.

袖子太短，太合身了。

Something that is " too form fitting" means it's too tight; it fits against your body too closely, usually showing the shape of your body better.

“太合身” 的东西意味着太紧；它太贴合您的身体， 通常会更好地显示您的身体形状。

But if you don't have a body that is in good shape, well, you really don't want anyone to see it, so form fitting is a bad thing if you don't have a good body, and a good thing if you do.

但是如果你没有一个好的身材，嗯，你真的不想让任何人看到它， 所以如果你没有一个好身材， 那么合身是一件坏事， 如果你没有好身材，那么合身是一件好事你做。