jar, bottle
缾 centers on a container for liquids: a jar or bottle. The two given meanings are essentially the same object at different scales or materials.
缾 combines 缶 (a jar or pot) with 并, which likely contributes the sound. The character is a phono-semantic compound for a jar or bottle.
The left side 缶 is a jar, and the right side 并 looks like a bottle with a stopper. Together they make a jar or bottle.
For ヘイ, imagine a heavy jar that is hard to lift: heavy -> ヘイ, and the jar is so heavy you need both hands.