Questions & Answers about Na stole jsou tři hrnky.
Because stůl is the basic dictionary form, the nominative singular.
After the preposition na when you are talking about a fixed location, Czech uses the locative case, so:
- stůl = table
- na stole = on the table
So stole is the locative singular form of stůl.
Yes. Na can take different cases depending on the meaning:
- location → locative
Na stole = on the table - movement onto something → accusative
Dám hrnek na stůl = I’ll put a mug onto the table
In Na stole jsou tři hrnky, nothing is moving. The sentence only describes where the mugs are, so locative is used.