Can you tell me what is a mandolin?

The answer to your question is: Yes I can.

Even though you haven't asked for the description, I'm already here

so I might as well go through it:

A mandolin is a small stringed instrument. The strings are tuned like a

violin or the upper 4 strings on a guitar. There's a pair of two strings close

together for each pitch, and it's usually played by wiggling a pick between

the pair, to keep the note going.