This one is easy. As you may know, a axis of symmetry is the line where everything is the same on both sides of it. For this, you can use trial and error or just look at the points on either side. For y = -1, that will put the line in an awkward spot, crossing through 2 slanted lines instead of corners. For x = -1, this just cuts through the shape straight up and down and does not make the shape look equal on both sides of the line at all. Same goes for x = -2. I should probably mention, when you see a line that is described as "x = 1", it is a vertical line, because the line is constantly staying on the point x = 1, while having an infinite number of y-values. When you see "y = 1", it will be horizontal for the same reason, just flipped.
