작은 카페

은/는 marks the topic, what the sentence is about: 카페는 작아요 (as for the café, it is small). 이/가 marks the subject, often when someone or something is introduced or exists: 사진이 있어요 (there is a photo). 도 glues onto a noun to add 'also, too': 문도 오래됐어요 (the door too is old).

에 marks where something simply is: 주방에 있어요 (is in the kitchen). 에서 marks where an action happens: 주방에서 만들어요 (makes it in the kitchen). 에 can also mean 'from' with a verb of coming: 서울에서 와요 (comes from Seoul).

이다 glues directly onto a noun with no space, so it looks like part of the word. After a vowel it becomes 예요: 카페예요 (is a café). After a consonant it becomes 이에요: 지민이에요 (is Jimin).

오래되다 describes something old. Its natural form, 오래됐어요, uses the same ending Korean later uses for the past, because Korean talks about an old thing as having already 'become old'. Here it simply means 'is old'; the real past tense for other verbs comes later in the book.