What is a breaker block?
A bullish breaker forms in four steps. Price makes a low, rallies to a swing high, then drops to a lower low and takes the sell-side liquidity under the first low. After that sweep it rallies hard and closes above the swing high. The last up-close candle at that swing high — a bearish order block that did not hold — is the breaker.
When price comes back down into it, ICT traders look for longs. A bearish breaker is the same pattern upside down: a higher high sweeps buy-side liquidity, price breaks the swing low, and the last down-close candle at that low becomes resistance.