This question is based on Isaiah 6:2.
In the year that King Uzziah died I saw the Lord sitting upon a throne, high and lifted up; and the train of his robe filled the temple. 2 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. (Isaiah 6:1-2)
This is the only passage in the Bible that mentions seraphim. The word “seraphim” means “fiery ones”. Possibly they covered their faces as an act of humility as they are in the presence of God himself. Similarly, they may have covered their feet as a token of respect.