Psalm 16 describes a martial like relation with God. In language that brings to mind Ephesians 5, David describes his love for the Lord. That God guides his way and he is secure in him. And that not even death will end what God is able to do but that he can rescue even from there. 

This Psalm also brings to mind the hope of Jesus Christ. Indeed, the Psalm is the words of Jesus being spoken by his forefather David as Peter reminds us that David foresaw the resurrection of the Lord Jesus Christ.