On the first line in the chord object, you will see the name of the chord and after the “/” comes the inversion
and in the line below you have the Bass note.

The inversion indicates what note of the chord is to be played first, if it is identical to the key of the chord it is left out.
All notes keys in the chord is marked with green on the keyboard
And the bass is the blue or red dot, depending weather it’s contained in the chord or not.

There are 3816 different chords and a hand full of inversions pr chord , combined with a dozen of different bass notes, so there are plenty of room for making very advanced compositions.

As default ProChords uses flats (b) instead of sharps (#) but this can be changed (read How to change key of the song and notation style)
ProChords uses: Instead of:
maj major,M,∆
m minor,min
6 maj6, M6
7 dom, dominant 7
add / ( like in 6/9 )
dim -,°,b5
aug +, #5,+5

(“aug” stands for augmented – “dim for diminished -”sus” for suspended – “maj” for major and “m” for minor)

Read: How to delete a chord or Download ProChords for your iPhone