The Trinity is the biblical Christian doctrine that explains God as one being, made up of three persons: Father, Son, and Holy Spirit.
God describes Himself in mostly masculine terms: father, husband. The Hebrew names Yahweh, Elohim, Adonai, Kurios, and Theos are all linguistically masculine. At the same time, God also describes Himself in Job as giving birth, and in Isaiah as a mother. It's more complicated than simply "he" or "she."