Typically, the country-code top level domain (ccTLD) is just that — a country code. For instance, example.co.uk has content for the UK and example.com.au has content for Australia. Usually, registration of these domains is restricted. You have to prove that you are operating the site from the designated country. However, some countries have opened up registration to everyone. And of course, some top level domains, such as .com, are inherently generic. Google uses the location of a site in its ranking algorithms. A searcher in the UK is more likely to see sites from the UK in results. But for top level domains that aren’t restricted to a particular country, Google uses other signals, such as the location of the server in determining what country a site is most relevant for.