What does Paul mean by the expression "absent from the body and present with the Lord" (2 Cor. 5:6, 8)?

In 2 Cor. 5:1-11, Paul contrasts the earthly perishable body subject to sickness, diseases, and death with the glorious, eternal, immortal body which God has prepared for us in the heavens. The expression "absent from the body" means absent from the mortal body with its earthly infirmities. The expression present with the Lord means present in the glorious immortal body received at Jesus second coming.

2 Cor. 5:4 gives us a clue when the apostle longs for "mortality to be swallowed up of life." These words echo the words Paul wrote earlier in 1 Cor. 15:51-54, "we shall put on incorruption and this mortal must put on immortality." In 2 Cor. 5 as well as 1 Cor. 15, Paul longs for the immortality bestowed at Jesus' Second Coming (See also 2 Tim. 4:6-8).