A stop-loss is an exit rule set before (or immediately after) a trade opens: if price moves against the position past a certain level, the position closes automatically, capping the loss at a known amount rather than letting it run unchecked.
Stops can be fixed (a set price or percentage from entry) or trailing (moving up as a winning position gains, locking in profit while still giving the trade room to breathe, see chandelier exit). zengtrade's engine sizes stops as an ATR multiple rather than a fixed percentage, so the stop distance adapts to how much a specific coin is actually moving.
A stop-loss doesn't guarantee the exit fills at exactly that price. In fast markets, slippage means the real fill can be somewhat worse than the stop level.
Educational content, not investment advice. zengtrade is paper-first and non-custodial.