What does "he was wounded for our transgressions" mean?

So, what really happened on Good Friday? What (if anything) did Christ's suffering accomplish?

The New Testament authors... saw Christ as the suffering Servant of Isaiah 53, who suffered in the place of sinners, bearing the punishment they deserved, that they might be reconciled to God. -- William Lane Craig.

Read more on atonement theories: http://www.reasonablefaith.org/must-a-biblical-doctrine-of-the-atonement-comprise-penal-substitution#ixzz4eFSJlgCz