What does John 19:37 mean?

At Passover, Israel would sacrifice spotless lambs (Exodus 12:5), being careful not to break any bones (Exodus 12:46). This was symbolic and prophetic. Jesus, the sinless man (1 Peter 2:22) has been executed without His bones being broken (John 19:32–33). This is yet another fulfillment of prophecy (Psalm 34:20). John also noted soldiers gambling for Jesus' clothes (John 19:24; Psalm 22:18) and giving Him sour wine (John 19:28; Psalm 69:21) as references to the Old Testament.

Among the more traumatic things John witnessed at the foot of the cross (John 19:26) was a soldier impaling Jesus' side after His death. This resulted in a gruesome rush of fluids (John 19:34–35). Even though Jesus was also "pierced" by the nails used in crucifixion, the spear wound was a dramatic fulfillment of yet another Old Testament prophecy. The passage John has in mind is Zechariah 12:10. This section of prophecy refers to an eventual realization, by all of Israel, that they have "pierced" their own King and Messiah.

The cynical claims of Jerusalem's religious leaders (John 19:15) and the sarcastic sign placed on Jesus' cross (John 19:19) contribute to this sense of rejection.