Learn Swedish: Gardinen ligger ju på nattduksbordet. - The curtain lies on the nightstand, you know.

ligger is an intransitive verb, meaning it does not take a direct object. It describes the state of the curtain resting on the table (it is lying there). You would use the transitive verb lägger (to lay or put) if someone were actively placing the curtain on the table, like in the sentence Jag lägger gardinen på bordet.

Could I just use är instead of ligger to say the curtain is on the nightstand?

You would be understood if you said Gardinen är på nattduksbordet, but Swedish strongly prefers positional verbs like ligger (lies), står (stands), or sitter (sits) to describe where physical objects are located. Since a curtain rests flat, it ligger.

How does the word ju change the meaning of the sentence?

ju is a small particle used when you expect the listener to already know or agree with what you are saying. Here, it adds a tone of obviously or as you know. It makes the statement sound less like brand new information and more like a gentle reminder about where the curtain is.

Why is there an s in the middle of nattduksbordet?