The term describes a region, not a precise level. Above a cluster of equal-highs, below a prior-day-high-low, or around a round-number-level, the order book tends to hold stop orders and breakout orders that will execute if touched.
Large participants who need to move size prefer to transact where there is something to trade against, so price often travels toward these areas rather than away from them. That is the argument behind targeting obvious levels rather than avoiding them.
Understand the epistemic limit: retail traders cannot see resting stops. The pool is inferred from the chart, not observed. Treat it as a reasonable guess about where activity will concentrate, not as data.
Related: liquidity-sweep, equal-highs, equal-lows, round-number-level, order-book