This is a big box around things, which can be called the national character box, the big mouth box and the surrounding character box.
Since it is to enclose things, derivatives generally have the meaning of wrapping and enclosing. We are trying to disassemble the word "prisoner". Is there a person in the big box? This man is surrounded and is not allowed to go out, that is, he is imprisoned. In common parlance, he was imprisoned. This is the prisoner.
This is the word mouth, mouth mouth, door mouth. At first, the word meant mouth. No matter what shape Zhang Kaicheng's mouth is, Chinese characters are always represented by a small box.
The box around the word is a big box, and the mouth around the thing is a small box, which is written outside other things.
Video: network link
Oral video: network link