Four hashes at once
All four are worked out with your browser's Web Crypto (crypto.subtle.digest) and shown as lower-case hex, each with its own copy button. The length tells them apart: SHA-1 is 40 hex digits, SHA-256 is 64, SHA-384 is 96 and SHA-512 is 128. Changing one letter of the text changes about half the bits of every hash.
Exactly as typed
The hash is of the UTF-8 bytes of the text, exactly as it is in the box: a trailing space or line break gives a completely different hash, which is the usual reason two hashes of the same thing do not match. The hash of abc in SHA-256 starts ba7816bf, which you can use to check it against another tool.
Questions
Why is there no MD5?
Browsers' built-in cryptography does not offer MD5, because it has been broken for years and should not be used to check that something is genuine. SHA-256 is the usual choice now.
Can I hash a file?
Not here; it hashes text. For a file, a terminal does it: shasum -a 256 file on macOS and Linux, or certutil -hashfile file SHA256 on Windows.
Can a hash be turned back into the text?
No, but short or common text can be guessed by hashing guesses until one matches. That is why passwords should be stored with a slow password hash such as bcrypt or Argon2, not a plain SHA-256.