There are three candles on the altar, one for the Maiden, one for the Lady, and one for the Lord. This is the one for the Lord, and traditionally it's on the Western side of the altar. The HP (High Priest) usually stands on this side, too. Besides a candle, many folk put some sort of God Symbol here. This may be as simple as a pine cone or a bunch of nuts, or as elaborate as an intricate commissioned statue. Once again, it's up to the celebrant. There isn't one used here, because there really isn't room for one. But we do use on one our actual altar; although it varies from holiday to holiday.
The candles may be different colors for different occasions; but white, as shown here, is a good all-purpose color, because it contains all of the other colors.