C-x = (M-x what-cursor-position)

The code point in Unicode of the character at the cursor position is displayed in the minibuffer.
For example, if you place the cursor on the letter "あ" in the file of Shift_JIS and press 'C-x =', the following is displayed in the minibuffer.

Char: あ (12354, #o30102, #x3042, file ...) point=1 of 2 (0%) column=0

`12354, #o30102, #x3042` are decimal, octal, hexadecimal notation of the code point in Unicode of "あ".

C-u C-x = (M-x describe-char)

Display detailed information of the character at the cursor position in the split window.
For example, place the cursor on the letter "あ" in the file of Shift_JIS and press 'C-u C-x =', then the following is displayed in the split window.

             position: 1 of 2 (0%), column: 0
            character: あ (displayed as あ) (codepoint 12354, #o30102, #x3042)
    preferred charset: japanese-jisx0208 (JISX0208.1983/1990 Japanese Kanji: ISO-IR-87)
code point in charset: 0x2422
               script: kana
               syntax: w  which means: word
             category: .:Base, H:2-byte Hiragana, L:Left-to-right (strong), c:Chinese, h:Korean, j:
Japanese, |:line breakable
             to input: type "C-x 8 RET 3042" or "C-x 8 RET HIRAGANA LETTER A"
          buffer code: #xE3 #x81 #x82
            file code: #x82 #xA0 (encoded by coding system japanese-shift-jis-dos)
              display: terminal code #xE3 #x81 #x82

`code point in charset: 0x2422` represents the code point of "あ" in character set JIS X 0208,
`buffer code: #xE3 #x81 #x82` represents the encoding in the buffer (UTF-8),
`file code: #x82 #xA0` represents the encoding in the file (Shift_JIS).