What does it mean to be still and know that I am God? What does it mean to be still? What does it mean to know that God is God?

It doesn't mean anything sensible. It's just one of the rantings of Yahweh, who is one of the children of God Almighty.
However, the DOCTUFOS OF TRUTH gives us a reason why a god/goddess is not totally wrong if he or she claims to be God Almighty.

DOCTUFOS: Parables of Otem 19:21-27


21. Now do not judge the gods when they solely called themselves the Almighty God rather than a part of it. For many of them are confused concerning all the things they saw in their lucid dreams before they found themselves in the physical planets.
22. Now you humans, judge it yourself, if all you had before coming to existence on earth are just lucid dreams, would you take the things in your lucid dreams as realities in the long run?
23. For so were the gods who were not born. For all they saw before their existence in the physical realms were some communications with a being who made itself in the form of them and communicated with them.
24. And he told them to go and explore all the outer universe, rather than remaining forever in the inner universe.
25. And so did they fly out of their lucid dreams and came into the worlds of physicality.
26. And many of them held that they had a higher consciousness over them which they saw first in that lucid dream. But with time, they disbelieved the dream because they did not see the being who commanded them to explore anymore.
27. But that being who sent them to explore and make findings is God Almighty. And he has mixed up with all things and there is nothing which can be called God in isolation and there is nothing which is not a part of God. Therefore the summation of all things is God.