Learn Finnish: Pidämme uudesta olohuoneestamme.

It combines three parts: the noun olohuone (living room), the case ending -sta, and the first-person plural possessive suffix -mme (our). Notice the order: in Finnish, the case ending almost always comes before the possessive suffix!

The English translation says "our", but the word meidän is missing from the sentence. Is that normal?

Yes! When you use a first-person or second-person possessive suffix like -mme (our) or -nne (your, plural), you can completely drop the separate pronoun (meidän or teidän). The word olohuoneestamme already means "our living room" all by itself.

Why do uusi (new) and olohuone (living room) take the -sta ending?

The verb pitää (to like) requires the thing you like to be in the elative case (ending in -sta or -stä). Because the adjective uusi describes the living room, it has to match the noun and take the exact same case ending.

How does the word uusi (new) change into uudesta?