en_tn_condensed/mat/11/02.md

Now

This word is used here to mark a break in the main story line. Here Matthew starts to tell a new part of the story.

when John heard in the prison about

"When John, who was in prison, heard about" or "When someone told John, who was in prison, about." Even though Matthew has not yet told the readers that King Herod put John the Baptist in jail, the original audience would have been familiar with the story and understood the implicit information here. Matthew will give more information later about John the Baptist, so it is probably best not to make it explicit here.

he sent a message by his disciples

John the Baptist sent his own disciples with a message to Jesus.