Seraphim is the plural of Seraph. They are the highest ranking of angels and have 6 wings as described by Isaiah 6:2:
I saw the Lord sitting upon a throne, high and lifted up; and His train filled the Hekhal
(sanctuary). Above Him stood the Seraphim; each had six wings: with two
he covered his face, and with two he covered his feet, and with two he
flew."