Learn Portuguese (Portugal): A chave não está no quarto.

In Portuguese, we always use the verb estar (not ser) to talk about where something is located. Since we are talking about the physical location of the key, we use the 3rd person singular form, está.

What does no mean in this sentence?

The word no is a mandatory contraction (a combined word) of the preposition em (in/on/at) and the masculine word for "the", o. Together, they mean "in the". Because quarto (bedroom) is a masculine noun, we use no instead of the feminine na.

Why does não come before the verb está?

In Portuguese, to make a statement negative, you simply place the word não directly before the verb. It is much simpler than English because you do not need extra helper words like "does" or "is not".

Why does está have an accent mark?

The acute accent on the last letter tells you to stress that final syllable when speaking. This is very important because está means "is", but without the accent, esta is a completely different word meaning "this", which is pronounced with the stress on the first syllable.