商店(shāng diàn) - shop, store in Mandarin

商店 (shāng diàn) is the general word for a shop: a premises that sells goods to the public. It is neutral and slightly formal, the word a textbook or a sign uses.

The measure word is 家, as with most businesses: 一家商店, 那家商店. Learners who reach for 个 are understood but marked out immediately.

The trap is over-using it. In real speech Chinese people usually name the specific kind of shop rather than saying 商店: 超市 for a supermarket, 书店 for a bookshop, 便利店 for a corner shop, 花店 for a florist. Notice that 店 does the work in all of them. So 我去商店 is correct but a little vague, rather like announcing that you are going to a retail premises. Say where you are actually going and you sound far more natural.