Nothing special, just a super market with all you need ok quality, good price.
Be nice to people working there. Say "hola" and "gracias" if you don't know any spanish.

PRO TIP:
Bring Your Own Bag

Make sure to bring your own reusable bag, eco-bag, backpack, or whatever you prefer to carry your groceries home. In Argentina, supermarkets don’t provide plastic bags for free. Depending on where you're from, this might not be news to you.

However, it’s common to see tourists complaining to cashiers about this policy. If you’re also not a fan of reducing plastic waste in the world, you can either buy a recycled fabric bag right at the store or simply bring one from home.