Here's a simple way to think about the difference between
shade and
shadow, Maddie:
Shade is an uncountable noun and it's any not-well-defined area where light is blocked. Usually we're talking about sunlight being blocked.
That's why we say if you're standing under a large tree where the branches and leaves are blocking the sunlight from touching the ground, we say you're standing
in the shade (of that tree).
Shadow is a countable noun and it means a darkened area on a surface (e.g., a floor, a wall) that clearly or more-or-less clearly shows the outline of some object that is blocking light from reaching that surface.
For example, if you're standing outside on a sidwalk at, let's say, 4:00 p.m. on a sunny day, your body will block the sunlight from touching the sidewalk in a certain area, and if you look down at that area, you'll see the outline of your body. That's a shadow.
Now, although technically your example sentence can work with the word
shadow, it seems a little odd because we don't normally consider a gate creating a shadow -- even though it can. As long as it's blocking the light from reaching the ground and you can clearly see the form of the gate outlined in that dark area on the ground, it's a shadow.
I hope all of this helps clear these words up for you.
