This is the 33rd most frequent Portuguese word.
quando
"When."
Here, 'quando' is used as a conjunction to indicate the time when an action will occur.
Quando você vai ao mercado, pode trazer pão?
When you go to the market, can you bring bread?
In this sentence, 'quando' appears in an indirect interrogative clause, introducing the part that specifies the time.
Eu sei quando ele chega.
I know when he arrives.
Here, 'quando' is used as a preposition in a temporal phrase describing a past period.