Jacks or Better is the standard video poker game and the one worth learning first, because it has a correct play for every hand. You're dealt five cards, choose which to hold, and the rest are replaced — a pair of jacks or better pays, and the payouts climb from there to the royal flush.
Unlike a slot machine, your decisions matter. Which cards to hold from a given deal has a mathematically best answer, and playing it well is a genuine skill.
The minimum paying hand is a pair of jacks. A pair of tens or lower pays nothing, which is what shapes the whole strategy.
Yes — every deal has a mathematically optimal set of cards to hold, which is what separates video poker from a slot machine.
No — this is a free game with virtual credits and nothing to deposit or withdraw.