A Filter Bubble is a personalized search that appears when a user searches in a search engine like Google or Bing. The search engine attempts to guess what the user wants to search based on their past search history, location, past click behaviour and a will tailor the result according to the data. For example, when you start typing "game " in a search engine, you probably will see "game of the thrones" appear. When using the search engine more frequently, the filter bubble will grow larger and become more tailored as the search engine gets more information about your searching behaviour.
Nowadays, all search results are personalized. This means that if two users search "apple", they may get very different results. One filter bubble might show the Apple iPad, and the other filter bubble might display organic apples. Even when you are not logged into your google account, Google still has information about your location, the browser you are using, and the type of computer you are using. Based on the information above, Google's search engine will have your search results personalized. There is no "standard" google anymore.
A filter bubble eases a users search process as it displays the wanted results faster, and they don't need to type all the words in the search engine. Filter bubbles make it very easy to navigate quickly, you can just type one word and open the website you want. For some, losing control of what you see may seem as an issue but you can still simply search these terms and navigate to these sites without using the suggested search queries.