So I've got a question that may seem fairly elementary - I'm looking at AirNav and I see that quite often airports have ratios attached to obstruction clearance. For instance:

"Obstructions: 16 ft. trees, 334 ft. from runway, 309 ft. right of centerline, 8:1 slope to clear"

I've figured out how to calculate that ratio but what, exactly, does it mean? Any explanation in layman's terms would be most appreciated!