A jokerless hand does exactly what the name says: built entirely from tiles you actually need, with zero jokers propping anything up. Some hands on the NMJL card (the ones marked "C," for concealed) don't allow jokers at all. Every other hand technically allows them, unless you're choosing to skip one you could use.
Playing jokerless is genuinely harder. You lose the safety net of swapping in a joker for whatever tile you're missing, so the hand takes longer to build and stalls more easily. But there's a payoff: most tables score jokerless hands higher, and pulling off mahjong jokerless off the wall is one of the better feelings in the game.
If you're still newer to this, don't force jokerless on purpose yet. Get comfortable with the card first. The bonus points aren't going anywhere.
New to the table? Start with mahjong terms explained or our step-by-step guide to American mahjong.