Sobreesdrújula refers to words where the stress falls on the third to last syllable.
For example:
* "Cállate" (the stress is on the "ca")
* "Teléfono" (the stress is on the "le")
* "Hablaré" (the stress is on the "ha")
In English, there is no equivalent term. We would simply say that the word is stressed on the third to last syllable.