Graph the line y = -3x - 2.



Everything in the coordinate plane what is below this line or lies at this line, is the solution set.



In other words, all the points (x,y) that are below this line or lies at this line, form the solution set.



Or, which is the same, all the pairs of real numbers (x,y) that represent the points (x,y) that are below this line 
or lies at this line in the coordinate plane, form the solution set.



You can paint that half-plane by any color you want to represent the solution set visually.

    "coordinate plane", "a solution set", "below the line", "at the line", "half-plane" and "to paint the half-plane into some color".