The “Insurance” side bet is available in virtually all blackjack games. You put money down for insurance when the dealer has an Ace showing as their first card, if you think that the dealer will get a blackjack. The bet pays 2:1 if the dealer does get a blackjack, and loses if they don’t.
What are the chances of a dealer getting blackjack? This can be affected by the number of decks played in the game, what the current “count” is, and how deeply the dealer penetration of the cards goes. To get a blackjack a dealer needs an Ace (1 chance in 13 = 7.7%) and a picture / ten card (4 chances in 13, but only makes a blackjack when an Ace is present already = 30%). On average, the dealer will get a blackjack about once in every 23 hands. That’s also the same for a player.
Unless you’re a very experienced card counter, blackjack INSURANCE bets should be AVOIDED. The average house edge on the insurance bet is about 7% (on 4 decks and above). In the long run, not taking the blackjack insurance bet will save you money. Insurance is a premium paid to protect against an event that might or might not happen. In the case of blackjack insurance, the premium is simply too high to pay when compared to the relative risk.