Yes/no questions are formed by adding the particle vai at the start of the sentence; the word order stays the same.
Vai tu runā latviski?
Do you speak Latvian?
Other questions begin with a question word.
Kas tas ir?
What is that?
Kur tu dzīvo?
Where do you live?
Kad viņš nāks?
When will he come?
Kāpēc tu smejies?
Why are you laughing?
Cik tas maksā?
How much does it cost?
In speech, a statement can also become a yes/no question through rising intonation alone, without vai.
Short answers use jā (yes) and nē (no).
More question words
Kā jums klājas?
How are you?
Kurš tas ir?
Which one is it?
Ko tu dari?
What are you doing?
Cik tev gadu?
How old are you?