Learn Spanish (Latin America): ¿Qué es eso?

In Spanish, all question words like qué (what), quién (who), and dónde (where) always have an accent mark. This helps tell them apart from similar words used in statements, like the word que without an accent, which means "that" or "than".

Why is it eso and not ese or esa?

We use the neuter word eso (that) when we are pointing at something unknown or asking about a general idea. Since we are asking "What is that?", we don't know what the object is yet, so we can't choose between the masculine ese or feminine esa.

Why do we use es instead of está for "is"?

To identify what an object or concept is, we always use the verb ser (to be). The word es is the "it" form of ser. We use the other "to be" verb, estar, for locations, feelings, or temporary states.