Navigate to the "Scales" or "Modes" mode of the app:
Swipe up the sheet at the bottom of the screen and tap on the icon highlighted below.
If you don't see it, you must scroll the list of icons horizontally.
Intervals are useful for learning the "pattern" of the scale. If you know the pattern, you can transfer it to any other key.
The intervals relate to the "Ionian" major scale. So a major scale would have the intervals:
A "Mixolydian" scale, for example, the only tone which will change is the "7". It is a semitone lower. It is "flat" and thus gets a "b".
You can also display the note names.