Learn Portuguese (Portugal): O que é isto?

In Portuguese, we usually say O que (literally "the what") to ask "what" in a question. While que alone can sometimes mean "what", starting a question with O que is the most standard and natural way to say it.

Why use isto for "this" instead of este or esta?

We use isto when we don't know what the object is yet, which is exactly why we are asking! Isto is neutral, meaning it has no masculine or feminine gender. You only use este or esta when you already know the gender of the specific noun you are talking about.

Is the word order here different from a normal statement?

Yes! While normal statements usually follow a Subject-Verb-Object order, questions that start with a question word (like O que) flip this around. The verb (é) comes right after the question word, followed by the subject (isto).

How would I change this to ask "What is that?"

You simply replace isto with the word for "that". Use O que é isso? if the object is close to the person you are talking to, or O que é aquilo? if the object is far away from both of you.