Many Christians believe this verse is proof that there are two lords in this verse, they believe one is the Father and the other one is Jesus. This is not correct. 

Psalm 110:​1 A Psalm of David. The LORD says to my master, Sit at my right hand, until I make your enemies your footstool.

The context is about the victory of an earthly king. The first LORD is God, the Hebrew says YHWH. The second Lord (adoni) is the king, most likely David. God is saying to David, who is the master of the Psalmist that He will help him defeat his enemies, he will make the enemies his footstool basically he will trample them in battle.