Hi there! That would be the "damage" associated with choosing that path — so, if you've allocated yourself six points in "Sacks" and attempt to take the second option on the Ace of Pentacles (Go another way) but roll higher than a six, you'd need to roll the listed die (in this case a d6) and add that to your total Sacks "damage."
The first d10 you roll is used just to determine if you take harm, not how much harm you take.