Why doesn't the MacBook Air have a battery indicator on the device like MacBook Pro? I am used to the MacBook Pro having it turned off but I still know if the battery is full or not. What about the MacBook Air?
The MacBook Air has never, and the MacBook Pro has not since the 2013 revision, had a hardware battery indicator. The one that was found on those earlier MacBook Pros is no longer present. Both computers show the battery percentage in the Menu Bar, near where the time is displayed.
If the battery is not shown there, you can open System Preferences > Dock & Menu Bar > Battery and check "Show in Menu Bar."