Sol

In Twilight Princess, a Sol is an object that lights the Twilight Realm, similar to the sun of the World of Light. It is made of pure power and provides energy and life to the citizens of the Twilight Realm. The light of the Sols, later in the game, fuses with the Master Sword to create a "Light Sword."

Bringing the two Sols to the plaza in front of the Palace of Twilight enables their light to be infused into the Master Sword. Placing a Sol on special pedestals can cause platforms and steps to appear. Bringing a Sol (or the light-infused Master Sword) near to a cursed Twili will cause the Twili to revert to its original form.

Trivia
The word "Sol" originates from the Latin word for the Sun. Sol and its derivatives are are still used in a number of modern languages.

In Norse mythology, Sól is the goddess of the Sun, a daughter of Mundilfari and Glaur and the wife of Glen, and the name of the Younger Futhark s rune. The corresponding Old English name is Siȝel (/siyel/), continuing Proto-Germanic *Sôwilô or *Saewelô. The Old High German Sun goddess is Sunna, sister of Sinhtgunt (Merseburg Incantations). Every day, Sol rode through the sky on her chariot, pulled by two horses named Arvak and Alsvid. She was chased during the day by Skoll, a wolf that wanted to devour her. Solar eclipses signified that Skoll had almost caught up to her. It is fated that Skoll will eventually catch Sol and eat her, though she would then be replaced by her daughter. The earth was protected from the full heat of the sun by Svalin, who stood between the earth and Sol. In Norse belief, the sun did not give light; this was caused by the manes of Alsvid and Arvak.