Meaning:
Its source is Yoel, a Hebrew name meaning "Yaweh is God."
Narrative:
The four letters ''Y H W H'' (in their Hebrew forms) were used in the Jewish scriptures to represent the name of God, which was not allowed to be written, and was only to be uttered by priests at prescribed times during worship in the temple.
This ''Tetragrammaton,'' as it came to be called (from the Greek word for four, tetra), was often read as Adonai (lord). In time it came to be pronounced ''Yaweh,'' which is what scholars believe to be close to the original pronunciation.
The name is never pronounced by Jews who believe that the precise pronunciation of the tetragrammaton was lost. They continue to substitute the word ''Adonai,'' meaning my ''Lord'' or ''Master'' for it, until such a time as the lost information is rediscovered, presumably in the time of the rebuilding of the Temple.
As Yoel is based on the Tetragrammaton, it could be read as ''God is God,'' an affirmation that the God of the Jewish scriptures is the one and only God.