Unfortunately, it is a word that marketeers like, and overuse. It is therefore used to mean many things. What it means also varies a lot with the context. With cars, 'vintage' means something specific: a car from the period of 1919 to 1930 (wikipedia). With wine, it means a wine from one specific year, where that year is given on the label. With cheese, it just means 'aged' i.e. that it has been left to mature for some time. With clothing it means old style things that still have value today, as opposed to just 'old' or 'second-hand'.

"Vintage" is used to reference to material things that are old or past its prime which still holds value and/or style, usually when speaking of clothing, music, and cars. For example: "I bought a vintage Beatles t-shirt at the thrift store for five dollars." Or "My grandmother has a vintage couch from the 1950s." It is a noun but is not used to reference people or places. For example, "Rome is a vintage city," is incorrect.

The "vin" in "vintage" refers to wine. Every other meaning derives from that. The "vintage" means the year in which the grapes were harvested. Some years the grapes are better than others. A "good vintage" means wine made in a year when the grapes were particularly good. Over time, the phrase "good vintage" just got shortened to "vintage." A "vintage wine" means "a wine from a famously good vintage." Up to a certain point, wines are supposed to improve with age, so a "vintage wine" is often a relatively old wine. Generalizing to other things, then, "vintage" carries the meaning of being a) old, b) good, and c) from a particularly good year.