The G flat minor eleventh chord is a 6-note chord consisting of the notes Gb, Bbb, Db, Fb, Ab and Cb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Gbm11.
Interactive piano diagram for the G flat minor eleventh chord
Chords that are a subset of Gbm11. These contain less notes but all of them are included in Gbm11.