Potentiality is everything which can be whereas actuality is whatever already is.
As human beings we are a mixture of both we are actuality so far as what we are now, but we are always potentiality as far as what we can get to be.
For instance, a book after is done, does not have more potentiality because it already is what is suppose to be a book.
We human beings have the grace of always being in a struggle for self-realization because we are always potentiality of going beyond our actuality.
The only being who lacks of potentiality PER SE is God because He is all actuality. He is self-realized from and far beyond eternity.
As initial mover He does not need to reach anything He is everything, He is in everything, and He is far beyond everything.
Since we left our creator we became a dualism of potentiality and actuality. And we just will become full actuality when we come back to our Creator.
That is the final end of human being (as far as I understand. In other words my own personal philosophy). Whenever we come back to the Source, Initial Mover, God, or Heavenly Daddy (as I like to call Him) we will leave potentiality and become full actuality with Him.
If this is not my end as human being this life would not have any sense whatsoever to me.

TLW