decryption – How is the bcrypt algorithm decrypted?

I have a ton of encrypted or hashed texts and their decrypted or de-hashed forms(I don’t know which term is suitable in this case, if you can teach it as well, I really appreciate) via bcrypt. The thing I want to learn for the educational purposes only that how they are decrypted.

For example, the second text after the first colon is the salt.

$2y$12$./BuBOjyTdqysbY1eR7TC.pXlt7ySJW6PKlrfEw9CjnfD3tMHU2v.:lmnsqF0X:lol1234
$2y$12$./gIYLjuH5FborFLHJqT/e3oZ7DgXCfQyfYhjMURDxhW4zek1MHlG:UGMEYL0I:tomek2929
$2y$12$./mcc9eqh8tjRTWDcqkW0OLY6E./taB9gWc7Oz7NzzTibtgEO17Tu:ZFNgWoa5:Greenydon15

As far as I get, 12 is rounds here. I want to dive into this field as my M.Sc degree but before diving into, I want to be sure whether I can overcome. The answer with which you help will be insight for me.