I work in a grocery store five days a week
I have heard it is a retail store that primarily sells food
Basically it is with a lot of fresh produce and meat and dairy products 
I have heard that a grocer is a bulk seller of food
Bulk seller at retail prices 
Grocery stores often offer non-perishable food that is packaged in bottles, boxes, and cans do you sell stuff like that?
Yes lots of canned veggies and stored foods with a good shelf life
 Some large supermarkets also include a pharmacy, do you offer that as well?
Oh yes pharmacy, photo lab, beauty shop
i know that  Small grocery stores that mainly sell fruits and vegetables