What is the stripes of Jesus?

This is somewhat subjective in nature. It is widely accepted though, that the wounds on Jesus represent his disciples' sins being vindicated by his sacrifice for them.

The stripes Jesus received are part of the actual atonement of the sins of all who have ever lived, past, present, and future. They are not representative or symbolic!

Isaiah 53

5 But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.

40 = Probation