BipTask is an application for android that allows you to set up the connect Amazfit Bip with your phone to perform various actions through the Tasker.
With stock Amazfit Bip firmware BipTask provides you basic functionality. You can make Tasker actions that triggers while back button on you watch pressed one or more times.
If you want to use all the features of the application, for example, making custom watch apps with buttons, and link it with Tasker actions, you need to install BipOS firmware on your Amazfit Bip. You can find more info about BipOS here: https://myamazfit.ru/threads/bip-mnvolkov-bipos-en.1087/