What does Luke 2:35 mean?

Mary is listening to a direct prophecy given by Simeon, a man possessed by the Holy Spirit (Luke 2:25–27). Simeon's prediction is that Jesus' ministry will result in sharp division between people, even among Israel (Luke 2:34). This corresponds to Old Testament prophecies which indicated that some of God's chosen people would "stumble" in response to the Messiah (Isaiah 8:14). As Jesus preached, He noted this same effect (John 9:39). The intent of this division is to reveal whether each person is sincerely seeking God (1 Corinthians 1:23; 1 Peter 2:8; John 3:16–18).

Here, Simeon also notes that Mary will suffer intense personal pain as part of her role in Jesus' life. Some of that will come in the form of confusion and uncertainty (Mark 3:21, 31). Mostly, it will involve the horror of watching her Son's torture, crucifixion, and death (John 19:25–27).