THIS is a search for the word "Test" in Google:
THIS is a search for the word "test" in DuckDuckGo on the same computer.
So, what does it all mean? Well, it means Google is storing your query and using it to give you results you think are general, but in fact are specifically tailored for you. You can try this out yourself with the help of a friend by comparing your search results of the same search queries with each other. They will differ. A lot. You can already guess in which country the search query was submitted. You can also find out the screen resolution.
Does it matter? Not really. Only that your query information is stored. Forever. Who knows what they can do with it.