According to the Bible, the cherubim are one of the nine 'choirs' of Angels, and they are the second highest in the hierarchy of angels.
"They are the guardians of light, and of the stars. Remote from your plane of reality, still their light touches your lives, the divine light that they filter down from Heaven." (Ask Your Angels)
The word "cherubim" itself however comes from Sumerian, and originally had a slightly different meaning! "The most ancient references concerning forms of cherubim (in the Akkadian and Sumerian records) describe a mechanical security device (i.e., a robot) that was used to secure highly sensitive areas of the gods to which humans were denied access. This idea later evolved into a more abstract and spiritual one, displayed in the archetypal manifestation of a winged celestial figure who guards sacred places who is a servant of God." (Prism of Lyra)