This phrase is used here to mark the beginning of a new part of the story. If your language has a way for doing this, you could consider using it here.
## as he was praying ##
This refers to Jesus.
## praying alone ##
The disciples were with Jesus, but he was praying personally and privately by himself.
## And answering, they said ##
"And they answered him by saying"
## John the Baptist ##
Some languages may prefer to add "Some say you are John the Baptist."