As others have said … Augmented.
It is a triad with a #5.
Eb = 1, 3, 5 = Eb, G, Bb
Eb + = Eb, G, B
Do you read any standard music notation? If yes, do you see how the melody line through that bar is mainly on the note G before walking up to B when the G major chord comes along? Playing Em then Eb+ then G/D gives a chromatic movement in the bass (E → Eb → D) and provides chords that have chord tones of G then B, in harmony with the melody.
I wrote a brief post to illustrate two augmented triads here: Triad Chord Theory - #28 by Richard_close2u