You will be charged for your share of any shared expenses for services such as cleaning communal areas, gardening, pool maintenance etc., lift maintenance, electricity for lifts and communal lighting (stairs & corridors, for example), building insurance if you are in an apartment building, etc.etc.
When the property is officially handed over by the developer, an adminsitrator is normally appointed, who will work out an annual budget for all these kind of expenses. Your share of the budget will be calculated according to the coefficient (%) stated on your esctritura (deed).
As for how much you will pay - how long is a piece of string? It all depends on what facilities the community has, and between how many properties the cost will be divided. Some members here pay low charges, maybe €30 per month. Others may pay 10 times that!
Welcome to the forum, hope you find all the answers you need here. Who's the puppy? Real cute!