lane, alley, side street
衚 centers on a narrow urban passageway: a lane, alley, or side street.
衚 combines the enclosure 行 (going, street) with 胡, which likely contributes the sound. The character is a phono-semantic compound for a type of street or alley.
The outer 行 suggests a street or path, and the inner 胡 looks like a narrow, winding passage. Picture a small alley branching off a main road.
For コ, imagine a small child (子, こ) playing in a narrow alley: 子 -> コ, and the child runs down the side street.