This picture shows three wise men behind Jesus. They presented unto him three special gifts: gold, frankincense, and myrrh.
But the Bible text doesn't say how many wise men was there. We can find this event in Matthew chapter 2:
Now when Jesus was born in Bethlehem of Judæa in the days of Herod the king, behold, there came wise men from the east to Jerusalem,
saying, Where is he that is born King of the Jews? for we have seen his star in the east, and are come to worship him. Matthew 2:1,2
And when they were come into the house, they saw the young child with Mary his mother, and fell down, and worshipped him: and when they had opened their treasures, they presented unto him gifts; gold, and frankincense, and myrrh. Matthew 2:11
So, why we say "Three Wise Men"?
Now when Jesus was born in Bethlehem of Judæa in the days of Herod the king, behold, there came wise men from the east to Jerusalem,
saying, Where is he that is born King of the Jews? for we have seen his star in the east, and are come to worship him. Matthew 2:1,2
And when they were come into the house, they saw the young child with Mary his mother, and fell down, and worshipped him: and when they had opened their treasures, they presented unto him gifts; gold, and frankincense, and myrrh. Matthew 2:11
So, why we say "Three Wise Men"?
It's just a tradition. And their names comes from a tradition too: Gaspar, Balthasar, and Melchior.
