You use SHA functions to take a large document and compute a "digest" (also called "hash") of the input. It's important to realize that this is a one-way process. You can't take a digest and recover the original document.
See Also
The 3 Ds and 3 Rs of security: Why You Need to Know ThemGuidance on Achieving Qualified Remote eSigning for eIDAS ComplianceThe Four Aspects of Information SecurityHere’s Why Quantum Computing Will Not Break CryptocurrenciesAES, the Advanced Encryption Standard is a symmetric block algorithm. This means that it takes 16-byte blocks and encrypts them. It is "symmetric" because the key allows for both encryption and decryption.
In other words, to conclude, SHA isn't encryption, it's a one-way hash function. AES (Advanced_Encryption_Standard) is a symmetric encryption standard.
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