Learn Turkish: Üç tane yeni sandalye var. - There are three new chairs.

In Turkish, whenever you use a number before a noun, the noun must stay singular. You never use the plural ending -ler or -lar after a specific number. So it is üç sandalye (three chair), not üç sandalyeler.

What exactly does tane do here?

Tane translates to item or piece and is a common counting word. While you could just say Üç yeni sandalye, Turkish speakers often insert tane right after the number when counting physical objects to sound more natural.

What is the correct word order when using numbers, tane, and adjectives together?

The number always comes first, immediately followed by tane. Any adjectives describing the noun come next, and the noun goes at the very end. That gives us the order: Üç (number) + tane + yeni (adjective) + sandalye (noun).

Does var change if we are talking about multiple things?

No, var stays exactly the same whether it means there is or there are. It does not matter that we are talking about three chairs; var never takes a plural ending.