I only stayed for a short while.
我就呆了一小会儿。
You were there quite a while (= a long time), weren't you?
你在那儿呆了很长时间,是不是?
"When did that happen?" "Oh, it was a while ago (= a long time ago).
“那是什么时候发生的?”“噢,是很久之前了。”
I haven't seen him for a while (= for a long time).
我已经很久没见到他了。
I'll be fine in a while (= soon).
我很快就会好的。