Encryption is the process of using a procedure to jumble up a message so that its meaning is hidden from anyone who intercepts it. Only the intended recipient should know the procedure for un-jumbling it to make it readable again.
This topic is always explained in terms of Alice, Bob and Carol. Alice and Bob want to exchange a message, and they know that Carol might see it, so they need to encrypt it so that she can't tell what the message says.
In terms of Coronation Street, Bob and Carol are probably married, but he is having an affair with Alice. If you also imagine that it turns out that Alice is revealed to be Carol's mother, Bob and Carol are unknowingly brother and sister, and that lots of characters you can't remember the names of spend most of the time shouting at each other, you can spare yourself the experience of watching that or any other soap.
In technical terms, the original message is called the plaintext, the algorithm or procedure you use to encode it is called the cypher, and the resulting jumbled up message is the cyphertext.