It simply means that Christ is uniquely special to God and has
his authority. To sit at the right hand of an earthly king was a
place of honor, denoting special trust, authority from, and
relationship with the king. It was something that was understood
without needing explanation at the time. If you were to sit at
the right hand of the King meant that you acted with his
authority. Those who came to you would treat you with respect
and obedience, as if you were the king yourself. It's one of the
many demonstrations in the Bible, which is not readily
understood by us in our time that made perfect sense to the
culture as it was then. There's an article that explains it a
bit differently, with more detail here:
http://www.letusreason.org/onenes10.htm This is an excerpt: To
sit at ones right hand means a place of authority, it was a
place of honor it meant dignity and rulership. Throughout the
O.T there is used what are called anthropomorphism to describe
God in some function or characteristic. this is figurative