-2+(-6) is 6 units from -2 in the negative direction
Moving in the negative direction means that the a negative number is added (or simply subtracted)
When you move in the negative direction in a number line, the numbers are getting smaller
The starting point in -2+(-6) is -2. Then -6 is added from -2 (or -2 subtracted 6)
So -2 is moved in the negative direction 6 units.