This is the 106th most frequent German word.
wer
"Wer" means "who" in English.
In this sentence, "wer" is used as the nominative subject of the verb "hat gelegt," asking for the identity of the actor performing the action.
Wer hat das Buch auf den Tisch gelegt?
Who put the book on the table?
Here, "wer" introduces an indirect question embedded within the main statement, functioning as the subject of "wird kommen."
Ich frage mich, wer kommen wird.
I wonder who will come.
In this example, "wer" is part of the indefinite pronoun "wer auch immer," equivalent to "whoever," referring to an undefined or unknown individual.