Galand is a demon who is a member of the Ten Commandments, a group of elite warriors of the Demon Clan handpicked by the Demon King himself. He was sealed away along with the rest of the clan in the Coffin of Eternal Darkness until he was set free by Hendrickson.
Galand has the power to turn people into stone if they lie to him.
(Source: Nanatsu no Taizai Wiki)