Whatever is inside the absolute value, you just remove the negative and that's the result of that absolute value expression. It represents the distance on a number line. So for instance -11 is 11 units from 0, which is why |-11| = 11.
You create two equations as you want the left hand side (LHS) to equal 0 (RHS), thus if one of the brackets becomes 0 it will result in the whole LHS beocming 0 as the brackets are being multiplied (anything multiplied by 0 = 0)
