The English name is bit.
"C language says that char is 16 bit" may be a misunderstanding between Chinese and English.
There is a concept of "character set". For example, in the ASCII character set, one character is 8 characters, and the Chinese double-byte coded character is 2 bytes of 16 characters. There are other coded characters in the box, which may be several bytes.
Characters are called characters in English. Someone may be confused. The character in a set is 16, but for char it becomes 16.
C language can use sizeof(char) to calculate the number of bytes occupied by char. You can output it and see:
printf("%d ",sizeof(char));