No, it makes no sense Silver and it wouldn't be an 'idiom' anyway. 'Idiom' means a special way of saying something. Please explain what meaning you want to express.
What’s buffet?
-Buffet is a kind of self-supporting meal.
It looks as if you need to revise the topic 'How to Ask About' as well as the use of articles especially the indefinite one. Never mind, though! We expect a lot from you and you take risks which is one of the signs of a good learner.
The expression 'Never mind!' is an idiom. You don't know what it means until it's explained to you even if you know each word.