In this piece of "art", there are a lot of things going on. There are 6 separate equations, as seen below, and each equations is technically

*2 equations*put together. For example, in the first equation the two parts are -6 =< y and y =< 6. The first half would form the line at -6 and then shade up, while the second half would form the line at 6 and shade down. The same happens with the second equation (-6 =< x =< 6), but instead it is formed horizontally. For the last four, the equations are also two smashed into one. Again, -x =< y and y =< x. The first draws a line at -1x and shades down, while the second draws a line at 1x and shades upwards forming a triangle. This is true for the other three quadrants. Put them all together and you get a picture that slightly resembles the British flag.