guitar chord
E♭dim7
Three minor thirds stacked. The seventh is doubly diminished, which is why it is written with a double flat.
Written the other way round it is D♯dim7 — the same twelve keys on a piano, a different piece of notation.
Every fingering that fits a hand
xx1212
moderate · barre
x6757x
hard
bcdbdb
hard · barre
bcabxx
hard
bcdbdx
hard · barre
What is true of it
E♭dim7 is E♭, G♭, B♭♭ and D♭♭ — 1, b3, b5 and bb7 counted from E♭.
B♭♭ and D♭♭ are double flats, and they have to be: every letter from E♭ upwards is used once, so the b5 cannot be written any other way.
The easiest of the 5 fingerings below is xx1212: 3 fingers, one of them barring the 1st fret, held at the 1st 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.
3 of the 5 need a barre.
2 strings stay silent.
Where its notes are on the neck
The brass dots are E♭, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
E♭dim7/G♭
20121x
E♭dim7/B♭♭
x01212
E♭dim7/D♭♭
x3424x
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.