Google is a big company and does a lot of things now.
They started as a search engine. A search engine is a computer program called a spider which records information in a data base indexed by alphabetical order and by importance determined by the instructions given.
A spider can be given directions about what to look for and how to rate the value of the information and that is called an algorithm... what to place importance upon.
Google has large servers that host their spiders which continuously crawl the internet and record what they find and that's a search engine where you can ask it for information based upon words.