A pertinent question I thought. Abila is now known as Tel Abil and it is located to the east of lake Tiberias (the Sea of Galilee), some way north of Aelia Capitolina (Jerusalem) and the Dead Sea.
It possibly formed part of an unofficial alliance of 'ten cities' from around the time of Pompey, although just how loose this grouping is can be witnessed from the disagreement over which ten cities actually constituted the Decapolis.
Pliny the Elder lists Damascus, Canatha, Scythopolis, Pella, Gadara, Hippus, Dium, Philadelphia, Gerasa and Raphana - but not Abila! An inscription dating to 133/4 AD however names the city 'Abila of the Decapolis'.