Very little is known of Ra. He is one of the oldest non-Primordial gods and has little interest on the daily events of the universe.
He was present when Noriko Null addressed the Assembly of the Nine Gods; while he abstained from taking a position to many issues presented before the Assembly, he surprised everyone by supporting Null's search for the Dragon Tomb.
His interest was short-lived, as he did not attend the following Assembly to discuss the fall of Tiamat. 
As one of the Nine Gods, Ra is one of the most powerful gods in the Universe.
Immortality and invulnerability: Ra doesn't have a physical body, existing as pure energy. If he needs to interact with the rest of the universe, he creates an armor of solid light.
Telekinesis: Ra can move objects with his mind.
Infinite energy: Ra has access to an inexhaustible energy source. The full extent of his power is unknown, but he created an entire star using his own energy.
Universal translator: Ra can understand any language instantly.
Teleportation: Ra can teleport across galactic distances, reaching the Large Magellanic Cloud from the Karnak Galaxy despite the millions of light-years of distance.
He has spoken only once in the series, saying one word. Apparently it's been ages since he has said anything.
- Beyond The Impossible #200, "The Throne of the Universe": attends the Assembly of the Nine Gods