You are letting someone know that something is required to be done at the present time. 你让别人知道某事需要现在去完成。

Here are some examples:  这里有一些例子： 

"It's time to say goodbye." 

 是时候说再见了。

"It's time to ask for a raise."

 是时候要求加薪了。

"It's time to collect our money."

 是时候收钱了。

"It's time to cheer for our team."

 是时候为我们队欢呼了。

"It's time to change the clocks." 

是时候更换时钟了。

"It is time to decide what to do."

 是时候决定做什么了。

"It is time to enjoy ourselves."

 是该我们享受的时候了。

"It is time to fill me in on what's going on."

 是时候告诉我发生了什么事了。

"It is time to help out."

 是时候该帮忙了。

"It is time to join a gym."

 是时候该参加健身了。