The word "拖后腿" is formed by combining the character 拖, meaning "to drag", with 后腿, meaning "back leg", creating a literal sense of "dragging the back leg". This literal image serves as a metaphor for hindering progress or causing delay, as if someone's movement is physically impeded by their own or another's leg being held back, thus directly deriving its figurative meaning from the concrete actions and body parts described by the characters.