Line-Pay Scatter is a hybrid feature that acts as a 'Scatter' to trigger a bonus feature like free spins, but its activation mechanism is like that of a regular 'symbol'.
The core of this feature is that it is not recognized simply by appearing scattered on the reels like a standard scatter.
It will only trigger the bonus if it aligns sequentially from the leftmost reel on a designated Payline.
This is a unique rule often found in classic slots.