Learn Spanish (Spain): ¿Os gusta bailar?

In Spanish, the verb gustar works differently than "to like" in English. Literally, this sentence means "Is dancing pleasing to you all?" The pronoun os means "to you all" (the indirect object form of vosotros). Because the dancing is pleasing TO you, we must use os instead of the subject pronoun vosotros.

Why is the verb gusta instead of gustáis if we are asking "you all"?

With gustar, the verb matches the thing that is pleasing, not the person who likes it! Here, the thing that is pleasing is the action of dancing (bailar). Because an action is treated as a single thing, we use the singular form gusta.

Would we use gustan if we asked about multiple actions, like dancing and singing?

No, when you are talking about liking actions (verbs in their basic dictionary form like bailar or cantar), you always use the singular gusta, even if you list more than one action. You only use gustan when you like plural nouns, like "apples" or "books".

Does the use of os mean this sentence is specific to Spain?

Yes! Os is the pronoun that matches vosotros (the informal plural "you" used in Spain). In Latin America, people use ustedes for both formal and informal groups, so they would ask ¿Les gusta bailar? instead.