What the fudge is public-key🔑 cryptography?

Have you ever wondered about:

1. What these keys were in the programming sense of things?

2. How can you take a random string consisting of numbers and alphabets and base the security of your system on it?

I have tried to explain just that using the example of actual physical lock and keys in this video:

Let me know in the comment section if that was helpful, Cheers!