An order block is the last candle of the opposite colour right before price makes a strong, decisive move. For a bullish order block, it is the final red (down) candle before a sharp rally that breaks the previous high. The idea is that big players left orders in that candle's range, so when price comes back to it later, that zone often acts as support or resistance.
In plain terms
It is the launchpad candle just before a big move. Price tends to come back and test that launchpad, and this alert fires the moment it does.
What triggers it
Three things must line up. First, the move out of the block must be strong (it covered at least 1.5x the ATR over the next 3 bars). Second, that move must break the previous swing point. Third, a later candle's wick must dip back into the block's original range without price having already closed through the far side of it.
How Signalix scores strength
The base score is 3 out of 5. We add a point when the higher-timeframe trend agrees, and a point when this is the first time price has tapped the block since it formed. Fresh, untested blocks tend to react most strongly.
When it no longer counts
If price closes all the way through the opposite side of the zone before coming back to tap it, we treat the block as "used up" (mitigated) and stop watching it.