a bit和a liitle都可以表示“一点”

a liitle即可以修饰不可数名词,也可以修饰形容词

a bit 只能修饰形容词,如 a bit small; 修饰不可数名词时要用a bit of ,如 a bit of rice

I should lie down for a bit, if I were you.

如果我是你，我就会躺一会儿。

Why don't you go upstairs and lie down for a bit?

你不为什么不上楼去躺一会儿呢？

And I'm mailing his wife a liitle present.

而且我会给他太太寄一份小礼物。