Hashing is the process of transforming any given key or a string of characters into another value.
Hashing is like hash browns.
To hash something is to chop it and mix it.
When you cook hash browns, you can take any potato, hash it up, and out comes hash browns.
You can't look at the hash browns and tell the cook exactly the size and shape and color of the potato used to create these hash browns, because no matter what the input of potatoes are, the end output will always be hash browns.
Hashing is the process in which a computer will chop up an input and produce a consistent output of equal length/value. Hashing is used for encryption, so for example, when you enter a password, instead of storing the exact password, you hash it so anyone who can see the stored password can't figure out what the true password value is.
This term isn't too relevant if you don't have a product yet, so don't waste your time over here! Head on over to some other words that are more important to learn before you have a product.
While hashing is more important with a live product, as you may require hashing as part of your product, the term is one you just need to know at a high-level. As long as your developers are aware of where you need to hash, you should be good to go.