吃午饭了

It’s time to have lunch; be going to have lunch now.

→ 吃
phrase Rare #26,453
It’s time to have lunch; be going to have lunch now. Here, 了 marks a new situation or a change in what is happening; it does not necessarily mean the lunch was eaten in the past.
CH: 我得去吃午饭了。
EN: I have to go have lunch now.

你的队伍准备吃午饭了?

Is your team about to have lunch?

— 精英部队 (2007)

我得去吃午饭了

I have to go eat lunch.

— 真爱至上 (2003)

他应该是去餐厅吃午饭了

He must have gone to a restaurant for lunch.

— 地球上的星星 (2007)

如果你明天有空,我们就可以一起吃午饭了。

If you're free tomorrow, we can have lunch together.