This is the 5241st most frequent Swedish word.
du
"You" (singular, informal).
Here, 'du' is used as the subject of a question referring to the person being addressed.
Hur mår du?
How are you?
In this sentence, 'du' is part of a statement describing the addressed person's condition.
Kan jag hjälpa dig, du verkar trött.
Can I help you? You seem tired.
Here, 'du' is used in a compound subject to denote the person included in the conversation.