MediaWiki:Botpasswords-summary

Bot passwords allow access to a user account via the API without using the account's main login credentials. The user rights available when logged in with a bot password may be restricted.

If you don't know why you might want to do this, you should probably not do it. No one should ever ask you to generate one of these and give it to them. For an overview of using BotPasswords with some common tools, see Wikipedia:Using AWB with 2FA.