Answer
A circle of radius 2 and center (0, 0, -1), contained in the plane z = -1, which is parallel to the xy-plane and 1 unit below it.
Work Step by Step
$x^{2} + y^{2} = 4$ would represent a circle of radius 2 and center (0, 0) in the two-dimensional xy-plane. In three dimensions, that equation alone would represent an infinitely tall cylinder. However, when combining it with $z = -1$, we get the usual circle but now contained in the plane $z = -1$, which is 1 unit below the xy-plane and parallel to it. The center of this circle would be at (0, 0, -1)
