what does this experience mean?

Songs you've heard in the past often evoke a sense of nostalgia. It's a weird feeling. 

The sense of smell is far better than sight or all the other senses for triggering a memory. A toffee apple, inside an old shed, even when blindfolded, will still bring back memories. It has been many years since I worked in France but one morning, I sat outside of a cafe and had a coffee as I read a paper. Every time I smell that particular coffee, I am back in France on that very street. A pic or a conversation about France doesn't do it, just the aroma of that same coffee.