The OM symbol symbolizes the first frequency that created the universe.
Sound is frequency, and the whole universe is made up of frequencies. In Judaism, the Creator speaks. In Christianity, there is the word and in Buddhism there is the Om. The enunciation of Om generates a sound, and this sound symbolizes movement and rest, which are once again the attributes of a frequency. It is interesting to note the relationship between the Om and the word mother in different languages
The OM symbol also has a meaning - the top symbolizes the start of creation, emerging from the vast emptiness.
The pendant also includes the Tibetan knot symbol, one of the eight symbols of Tibetan Buddhism. If you pull one side it will pull another part. In order to break the knot we need to free ourselves of our attachments.