Questions & Answers about Kytarista hraje moc dobře.
Kytarista means guitarist or guitar player. It is a noun for a person, like English pianist, violinist, etc.
- kytara = guitar
- kytarista = guitarist
Czech often uses endings like -ista for professions, roles, or people associated with something.
It is in the nominative singular, because it is the subject of the sentence — the person doing the action.
So in:
Kytarista hraje moc dobře.
the guitarist is the one who plays, so kytarista is nominative.