“那时候”用来说过去的某一段时间，意思很像英语的“at that time”。

"那时候" is used to refer to a certain period in the past, similar in meaning to the English "at that time."

我们常常说“那时候我还小”，来讲以前的事情。

We often say "那时候我还小" to talk about things from the past.