In English, we say 'excuse me' for all sorts of things. We use it to get someone's attention, to interrupt someone politely, to order in a restaurant, to move past people in a crowded place....the list goes on.
In Korean, the phrase for 'excuse me' is '저기요' [ jeo-gi-yo ]. This phrase is different to the English in that it is not as flexible; it can only be used to get someone's attention - usually just in a restaurant or shop. Whatever you do, don't do what one of my classmates did - this phrase should NOT be used to get the attention of someone senior to you, i.e a teacher or a boss, as doing so would be very disrespectful.