F/Eb (F Major over Eb)
Notes, from the bass up
Eb (bass)FAC
A slash chord names two things at once. The part before the slash is the chord your right hand plays, and the part after it is the single bass note for your left hand. Read F/Eb as F Major with Eb in the bass.
The bass note here is not part of the chord itself. Your left hand plays Eb while your right hand plays the plain F Major shape above it.