You can find MySQL's documentation here: https://dev.mysql.com/doc/
Article from the support category: MySQL
We strongly advice you to choose another password
The entered password is known in "Have I Been Pwned", which is a public database of leaked passwords on the internet.
Presumably, you (or someone else) have used the password before on another website, from where the password has been leaked, and the password is therefore no longer secure to use.
Enter your password here for more information: https://haveibeenpwned.com/Passwords.