Door Mr. Brian P. David
If we keep following the Lord through the valley of the shadow of death, He will ultimately endow us with a new heart and a new mind, filled with love and wisdom and prepared for heaven. That's what is pictured in this verse.
A "table" represents the parts of us that can be filled with love and wisdom. Oil represents loving what is good because we love the Lord, and to be anointed lets us be a representative of the Lord. A cup, like the wine that would typically fill it, represents true spiritual thinking centered on love to the neighbor. So we are filled by the Lord, loving Him, loving what is good, and overflowing with wisdom regarding life.
But what about the "presence of mine enemies"? The Writings say that even with the highest angels, the Lord cannot actually remove the possibility of evil from us without detroying our humanity. It's a complex idea, but essentially, the possibility of evil is what makes us different from the Lord, what keeps us separate. And he created us to be separate so that he could love us. So even in the beautiful state pictured here, our enemies – evil and falsity – are still nearby.