Learn Hardcore Korean: gageeseo keopireul jumunhaeyo.

In Korean, it’s common to omit the subject when it’s clear from context. Here, the speaker (“I” or “we”) is implied, so you don’t need to say 저는 or 우리는.

What is the function of 에서 in 가게에서? How is it different from 에?

에서 marks the place where an action happens (“at the store”).

에 can mark location of existence (“in/at”) or direction.
에서 specifically indicates the location of an ongoing action.

Why is 커피 followed by 를?

를 is the object particle. It shows that 커피 is the direct object of the verb 주문해요 (to order).

What is the dictionary form of 주문해요, and how do you conjugate it?

The dictionary form is 주문하다 (to order).
Since it’s a -하다 verb, drop 다 and add the polite present ending -해요 → 주문해요.

What politeness level is 주문해요? Are there other ways to say it?