When "주세요 (Ju-se-yo)" is followed by a noun, it means "Please give me (the noun)". This exact format is most commonly used when ordering something in a cafe, restaurant, or market.
이거 (I-geo), means "this". Just like the English translation, you can use this word as you point at an item that is near you. If it is far away from you, you need to use the equivalent of "that", which is 저거 (jeo-go).
Ha-na is "one", in one of the two Korean counting methods. You add this after the noun to specify how many items you want. Although the grammar might be unfamliar, remember that it comes in this order: