Mercadona: Mercadona is the largest chain supermarket in Spain and is very affordable for groceries.
Primor: Comparable to an Ulta. Stop in Primor to find makeup, hairdryers, and other beauty products.
Primark: Comparable to Target. This is a great place to find clothes for all occasions. Primark is especially great for inexpensive housing necessities like pillows, blankets, and storage.
Oysho: Comparable to Aerie. If you are looking for athleisure or swimsuits, Oysho is the perfect place. This Spanish brand offers stylish, quality pieces.
Shopping like a Spaniard: Shopping like a local means getting your fruits and veggies from a 'frutería' your meat from a 'carnicerías' and fish from a 'pescadería.' You'll find that your produce is fresher and cheaper than at supermarkets.
Other retail options:
Zara, Bershka, H&M, Lefties for clothing
Alcampo, Ametller Origen for groceries
MediaMart & FNAC for technology
*A reminder*
Before heading out to shop during siesta hours (2 pm - 5pm) or on a Sunday, remember to always check Google Maps to see if a store is open, as many will be closed during this time.