For we know that if the tent that is our earthly home is destroyed, we have a building from God, a house not made with hands, eternal in the heavens. (2 Corinthians 5:1)
Bible teaching on life after death is that we remain in the grave until the return of Jesus to earth (John 5:28-29).
Then we will be resurrected (Daniel 12:2) and, if faithful, will be given immortality (1 Corinthians 15:51-54). Our immortal bodies will be like Jesus after his resurrection (Philippians 3:21).
So in the context of the rest of Bible teaching, 2 Corinthians 5:1 is saying that if our mortal body (“earthly tent”) is destroyed, then God will provide an immortal body (“a house not made with hands”) which will last forever (“eternal”). In a sense, these bodies are now “in the heavens” in that they are with God. (See 1 Peter 1:4-5 and 2 Timothy 4:8 for a similar concept.) But when we receive our immortal bodies, we will be on earth (Revelation 5:10).
For more information, see Heaven and hell.