When people talk of a book's setting, what do you think they mean? My immediate answer would be Scotland in 1543 for the book I'm currently working on. Is that enough? For a swift answer in a verbal exchange, I think it is. If they want to know more, they'll ask.
If I had to write an article on setting, I would elaborate. Setting is important. I use everything I can to make the reader think "sixteenth century Scotland." After all, life in Stirling Castle has to be vastly different to living in a three bed detached today.
Setting is many things. It's dialect, delicately done, what they wore, how they ate, what they ate and if they did it with their fingers. What kind of plates did they have if they were rich? if they were poor? It's weather and seasons, heat and cold, farm yard smells, perfumes and sweat. Rich tapestries, and straw mattresses. All those things and more. It's how something feels - if you touch a horse, their skin is usually warm, sometimes hot if they're been running. If you see it, can you smell it, taste it, touch it and hear it? Imagine yourself into the pic and tell me if you can smell the pine trees, and hear the wind rustling through the grass. Actually, there was no wind. It was one of those hot, sticky, airless days when the insects are biting. All these thing make up the world of your story. Use them, but use them carefully.