Answer
This is the half space that lies to the left of the plane $y=8$.
Work Step by Step
This region is the set of all points $(x,y,z)$ that satisfy the equation $y\lt 8$. So this is the set of all points with $y$-coordinate less than 8.
We know $y=8$ is the plane that intersects the $y$-axis at $y=8$ and is parallel to the $xz$-plane. So since every point in our region has $y$-coordinate less than 8, every point must lie to the left of the plane $y=8$.
So our region is the half space that lies to the left of the plane $y=8$.
