데 is the plain, casual word for 'place, spot', and the clause in front says which one: 밥집 좀 유명한 데 있어요? 'is there a well-known place to eat around here?', 조용한 데 있으면 'if there's somewhere quiet'. 데 also means 'the part or point where': 홉이가 멈추자고 한 데 있잖아 'you know the bit where Hobi said to stop'. Careful with spacing — 는데 written closed is the completely different connective '…, and / but', which sounds identical.