Learn Portuguese (Portugal): O número é zero.

Not quite! In Portuguese, the z sounds the same, but the e is pronounced as an open "eh" sound, and the r is a single tap against the roof of your mouth (similar to the "tt" in the American English word "butter"). The final o sounds like a short "oo". Put together, it sounds roughly like "ZEH-roo".

Why is there an accent mark on the word número?

The acute accent tells you which part of the word gets the strongest emphasis. Most Portuguese words ending in -o naturally stress the second-to-last syllable. Because the stress actually falls on the first syllable here (NÚ-me-ro), the word needs an accent mark to override the normal rule and show you exactly how to say it.

Why do we use é here instead of está to say "is"?

We use é (from the verb ser) for permanent states, facts, and identities. The fact that this specific number is zero is a permanent truth, so we use é. The other "to be" verb, estar (which gives us está), is used for temporary states like feelings or current locations.

I keep mixing up e and é. How do I remember which one is used here?