wrapping enclosure, wrapping radical (no. 20)
勹 centers on the idea of wrapping or enclosing something, like a curved arm or container holding an object. It is primarily used as a radical in other characters to convey wrapping or enclosure.
勹 is a pictograph of a person bending over or an arm curving around something, representing the idea of wrapping or enclosing.
The curved stroke looks like an arm wrapping around something or a container enclosing its contents. Think of it as a wrapping enclosure.
For ホウ, imagine wrapping a precious object in a protective cloth and saying 'hold' as you secure it: hold -> ホウ.