Breakdown of Var du ledig igår?
vara
to be
du
you (singular)
igår
yesterday
ledig
off work / available, vacant (of a room)
Questions & Answers about Var du ledig igår?
Why do we use var here instead of är?
Var is the past tense of the verb vara (to be). Because the sentence is asking about yesterday (igår), we use var (were) instead of the present tense är (are). Luckily, Swedish uses var for all subjects, so you don't have to worry about choosing between "was" and "were"!
How does the word order show that this is a question?
To make a yes/no question in Swedish, you put the verb first, exactly like in this English sentence. The statement "You were" is Du var, but to ask "Were you?" you simply flip them to Var du?
Does ledig only mean "off work"?
It broadly means "free" or "available." When talking about a person's schedule, it means having a day off from work or school. You can also use it for things, like asking if a seat or a restroom is unoccupied.
What if I wanted to ask a group of people if they were off work?
You would need to change the pronoun to ni (plural "you") and add an -a to the end of the adjective to make it plural: Var ni lediga igår? In our sentence, it's just ledig because we are only asking one person (du).