In Spanish, 'costa' simply means coast, and it starts the names of Spain's holiday coastlines — the Costa del Sol, the Costa Brava — where huge numbers of British tourists have gone on package holidays since the 1960s. British newspapers then borrowed the pattern as a joke: take any stretch of coast, stick 'Costa' in front, and add a word that says what the place is really known for. So the retirement towns on the south coast of England became the 'Costa Geriatrica'; a coast with grey weather and rocks gets called the 'Costa del Concrete' or similar. The humour depends on the gap between the sunny Spanish original and the far less glamorous place being described, so it is gently mocking and sounds odd if you say it with a straight face. This is a British newspaper habit above all — headlines, travel columns, jokes about the weather. It is capitalised and followed by a made-up second word that the writer invents on the spot, so you are meant to work out each one fresh. (Quite separately, Costa is a large British coffee-shop chain, and a common surname in Portugal, Spain, and Italy — same word, different uses.)