Some of Jesus’s followers were together. They were Peter, and Thomas (whose other name was the Twin), and Nathaniel (a man from Cana in Galilee), and James and John (the 2 sons of Zebedee), and 2 other followers.
Jesus was talking about Judas Iscariot. He was one of Jesus’s 12 special workers. But Jesus knew that later on Judas was going to turn against him. Jesus knew that Judas was going to help Jesus’s enemies catch him.