What does Mark 3:19 mean?

At this time, Judas is just one of the disciples, but it becomes apparent he never understands who Jesus is. He takes on the role of treasurer, but only so he can steal the group's money (John 12:6). In the future, he will betray Jesus, handing Him to the scribes and priests to be tried and crucified. In return he receives thirty pieces of silver (Matthew 26:15). It appears that Judas doesn't know what the priests and elders have planned for Jesus. When he discovers Jesus is on His way to be tried and executed, Judas returns the money and kills himself (Matthew 27:3–5). Judas' payment and its eventual use to buy a potter's field is prophesied in Zechariah 11:13–14. He is replaced by Matthias, one of Jesus' regular followers, in Acts 1:12–26.

Modern society has come to associate the name "Judas" with everything evil. However, at the time of Christ, this was a common name. Thaddaeus the disciple was also called Judas. Jesus' half-brother Jude's name is a variant of the name Judas. And in the Old Testament, Judah, the name of both the man and the tribe, is basically the same name as Judas.

There are several different theories as to where the name "Iscariot" comes from. It may mean a bandit, a freedom fighter, or a liar, but it probably means "of Kerioth." Kerioth is the name of two different cities, one in south Judea (Joshua 15:25) and one in Moab (Jeremiah 48:24). Judas Iscariot may be the only disciple from outside of Galilee.

The word translated "betrayed" is from the Greek root word paradidomi. Literally, it means to "give over" or "deliver," often with treachery. It is also used in Mark 1:14 to describe John the Baptist's arrest. Later, Paul will use it to describe how he passes on the gospel (1 Corinthians 15:3).