And God raised us up with Christ
and seated us with him
in the heavenly realms
in Christ Jesus,
The phrase, "the heavenly realms" is translated "the heavenlies" in some other versions and in some other passages. After a little study, I believe that we could understand this best as heavenly citizenship. We are not actually there yet, but we might as well be. That is where our citizenship is. That is where we will end up.
But being seated there gives us the idea of permanence and authority. And we do have authority. Think of the context of this passage. We now have enough authority to say no to sin. We are no longer servants to sin, and to our sinful natures. For we have been seated in the heavenlies! Though we aren't there physically, we are seated with Christ now! And he has conquered sin and death for our good and for his glory.