What is true of it
Adim7 is A, C, E♭ and G♭ — 1, b3, b5 and bb7 counted from A.
The easiest of the 1 fingering below is 2323: 3 fingers, one of them barring the 2nd fret, held at the 2nd fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
Where its notes are on the neck
The brass dots are A, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Adim7/C
5320
Adim7/E♭
8989
Adim7/G♭
bcbc
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.