The bars around x + 4 mean absolute value.
This just means, how far away something is from 0.
For example:
|3| would still equal 3 because it is 3 away from 0.
|-3| would equal 3 as well because it is also 3 away from 0.
So basically for this equation there are two solutions. This is because |2| and |-2| would both still equal 2.
So:
x + 4 = 2 is one solution.
-4 -4
x = -2
x + 4 = -2 is the other solution.
-4 -4
x = -6
So the two solutions for x are -6 and -2, or the first number line.