Its the Alumbrado Barrido y Limpieza, it's a property tax for streetlighting, street sweeping and cleaining. Most landlords make their tenants pay this, it´s really unfair but it´s kind of customary here. It's due every 2 months or you can pay the whole thing up front for 1 year and it´s 10% less. Read your rental contract and see if you agreed to pay ABL, AySA (water fee), and expensas (maintenance). Landlords here (most of them) are s**t, and the big stinky kind at that.