Imagine a wall drawn on a 2D plane. We, as 3D dimensional beings are able to see over it because a 2D drawing has no width in the 3 dimension, and we're looking at it from the Z-axis. Similarly, a 2 dimensional being might look at a 1D world- a straight line- and a 1D "wall"- a dot on that line. A 2D being can see past the walls of the 1D world simply by looking at it from the y-axis, in which it has no width.

Therefore a 4 dimension being looking at our 3 dimensional world would see us similar to how we see a 2 dimensional world. Our world would have no width in the 4th dimension, allowing a 4th dimensional being to see everything- over all of the walls and through every room- by looking at us from the w-axis.