A 'stretched out arm,' as in Exodus 6:6, signifies omnipotence or divine power, because 'an arm,' when stretched out in the heavens, represents power from the divine, but when not stretched out, but bended, it represents power in the general sense. This is why divine power is often shown in the Word as a stretched out arm or a strong hand.

(References: Arcana Coelestia 7205)

It is hard for us to conceive this, but time does not exist in spiritual reality. Time is an aspect of physical reality that no longer constrains us in spiritual life, just as we are no longer constrained by our physical bodies in spiritual life. That is what "forever" means in the Bible. It doesn't just mean "for a long time," "for the rest of your life" or even "until the sun expands and destroys the earth and all life here." It means to eternity without end.