It is probably a good idea to start with an explanation and go from there. Login Software refers to applications and tools that are linked to log ins. They can be used to manage all your account logins, to sign you in automatically on sites, or to perform other tasks like generating secure passwords to make sure that passwords cannot be guessed by attackers.
The software comes in two major forms: First as web browser plugins and second as standalone applications for the desktop. Both types have their distinct advantages and disadvantages.