What do om symbol tattoos symbolize?

its a Hindu smbol that means absolute knowledge & all creation.

It represents perfection. It represents an all powerful, all knowledgeable, supreme being. It also means divine energy.

Its kind of line Neo in Matrix Revolutions, after he starts seeing everything in Orange glow. He starts reaching that state, that no Human is supposed to reach and it leads to his end or rather his freedom and liberation from a physical form ... to his Nirvana.