They mean that you rolled a 1 or a 2 as your total.
This is why rolling 1 dice is dangerous.
If you roll a 1 or a 2 on 1 dice, you auto fail.
If you roll a 1 and a 1 on 2 dice, you auto fail.
If you roll a 1, a 1, and a 1 on 3 dice, you only fail if you did not meet the casting cost.