How much money do you need to live comfortably in Spain?

Could you please enlighten me on the matter of financial sufficiency in Spain? I'm quite curious to know, approximately how much money would one require to maintain a comfortable lifestyle in this charming country? Could you elaborate on the cost of living, including housing, groceries, transportation, and entertainment? Also, are there any specific regions or cities within Spain that might have higher or lower living expenses? I'm interested in understanding the financial nuances of living in Spain and how they might differ from other parts of the world. Thank you for your insights.