There are a few ways to approach this. Without knowing more about your setup, I'd probably go for the Physics2DDirectSpaceState solution using
You pass it a your location and it'll tell you what objects it collides with. If you're using collision layers/masks, you can be filter it so that it would only see the Area2D you care about.
var space_state = get_world_2d().direct_space_state
var result = space_state.intersect_point(point)