23:11 What did Jesus mean by what He said here?

Here the Lord praised Paul for his faithful ministry in Jerusalem, and promised him that he would also be His witness in Rome.

This was confirmation that Paul would not be sent back to Jerusalem where he would be killed before he could stand trial (CP V12-15; 25:1-3).

See also author's study Paul the Apostle - a Chosen Vessel unto God in his book Advanced Studies in the Christian Faith (Volume 2).