Learn Dutch: Wie redt de kat als er brand is? - Who saves the cat if there is a fire?

This happens because of the word als (if/when). Als introduces a dependent clause. In Dutch, dependent clauses always send their conjugated verb (in this case, is) to the very end of the clause.

Why does the verb redt end in -dt?

The verb is redden (to save). To make the singular form for a third party (which we use for the question word wie), you take the stem of the verb and add -t. Since the stem is red, adding a -t gives you redt. You don't pronounce the extra 't', but you must write it!

What does the word er do in this sentence?

Here, er combines with the verb is to mean "there is". Just like in English, we say "if there is a fire" (als er brand is) rather than "if a fire is".

Why is there no word for "a" before brand?

In Dutch, brand (fire) in the sense of a destructive event or emergency is often treated as an uncountable concept. So, you usually say er is brand instead of er is een brand.

Could als mean "when" in this sentence instead of "if"?