By default, every event hit is considered as an interaction hit, even if such an event is not initiated by the user. If your page contains events which are not initiated by the users you but still need to track some of the key activities such as internal promotion view, the default value for non-interaction Hit is set to 'False' which implies that current event is included in bounce rate calculations. Since such events are not initiated by the users you would like to set non-interaction hit to 'true' which will not affect bounce rate of the page.