Literally, it means, "Thou givest me happiness." But in English, we don't give happiness, and we don't use thou anymore. So a better interpretation would be, "You make me happy." As a question it...
"DAS" = "Double After Split"
That means that the player has the option of doubling his wager on a hand that resulted from a SPLIT of two like cards.
This is advantageous to the player.