If something's new, it has never been seen or discovered or invented before. Anything can be new: a country, an idea, a product. If you spend half an hour watching TV, you'll see an incredible selection of new items being advertised.
There are lots of shades of meaning attached to new. For example, by its very nature something that's new is unfamiliar, and the two words are often used interchangeably. New can also mean something different from what has gone before — as in a new political strategy — or, as advertising would have you believe, something fresh and original, like that new and improved version of your favorite laundry detergent you just bought.