Learn Swedish: Är de gamla eller nya?

No, it doesn't! eller (or) is a coordinating conjunction. That means it simply links two equal parts of a sentence together—in this case, the two choices gamla and nya. It acts just like "or" in English and doesn't force any other words to move around.

Why do gamla and nya end in "-a"?

Because they are describing the plural pronoun de (they). In Swedish, adjectives have to match the noun or pronoun they describe. When describing plural things, you usually add an "-a" to the end of the adjective. So, the singular word gammal becomes gamla and ny becomes nya.

I usually hear native speakers say "dom", but it is written here as de. Why is that?

In modern spoken Swedish, the pronoun de (they) is almost always pronounced as "dom". You will write it as de in formal and standard writing, but you should say it as "dom". This is one of the most common and important pronunciation quirks for beginners to remember!

Why does the sentence start with the verb Är?

Because this is a yes/no question. Just like in English ("Are they...?"), Swedish swaps the order of the subject (de) and the verb (Är) to turn a normal statement into a question. A regular statement would be De är... (They are...).