Grab a bite
Meaning/Usage: To get something to eat
Explanation: "A bite" refers to food. This is a pretty literal so it is simply saying to get something to eat.
When do you want to go grab a bite?
I don't have much time, so let's grab a quick bite.
If you didn't have lunch yet, let's grab a bite to eat.
A:
Did you have lunch yet?
B:
Not yet. I'm swamped with work.
A:
You have to eventually eat so let's just grab a bite somewhere close.
Other Common Sentences
Let's go eat.
Where should we have lunch today?
Let's have lunch together.