People use password managers so that they don’t have to remember all the usernames/passwords of the websites they visit. Instead, they can just remember 1 password, and then access all the other passwords whenever they need. In addition to that, this allows you as a user to increase the length and the complexity of the passwords you use, because now, you no longer have to remember them, so you can make your Facebook’s password something like 21#^#Y3#^2h281+_0H^I@F!##YU&^ with no problem.
Also, some password managers offer other features that you can use. E.g: Auto-fill (automatically fill the passwords when you open the URL in your browser), synchronization between devices, team storage (sharing passwords between multiple people), smartphone integration, various types & tools of encryption, emergency codes.. And so on.
Traditionally, there are many closed-source proprietary password managers, and there are those which are open source.
It is good to see some newer password managers in the list and not just the same old ones we are used to seeing - see #^https://fosspost.org/lists/open-source-password-managers
Here's a good list of 9 open source password managers that you can use to secure your passwords. Using of these is a must, but which one would you choose?