A live dealer game is a video stream from a studio table with a betting interface layered over it. The dealer is real, the cards and wheel are real, and the outcome comes from physical events rather than a random number generator, which is the main reason players choose the format.
The technology doing the work is optical recognition. Cameras read card values or the wheel result and feed them to the game server, which settles bets against the interface you see. Latency between the physical event and your screen is why betting windows close a few seconds before the deal.
House edge does not change because a human is dealing. Live blackjack at standard rules carries the same theoretical return as its RNG equivalent, and side bets carry the same substantially worse odds they do anywhere else.
What does change is pace and minimums. Live tables run slower than RNG games, which reduces hands per hour and therefore the rate at which the edge applies, and table minimums are usually higher than the equivalent digital table.
The format suits players who want the pacing of a real table. It is not a better-odds product, and any site describing it that way is selling rather than explaining.