Google can help you when you don't know the exact spelling of a word.
For example you are looking for the word "melanoma", but you don't know the exact spelling. Something with a 'm', an 'e' and 'a' that's all you know.
You know it has something to do with cancer and you can spell the word cancer.
So in the search box of Google you type the word "cancer".
Google gives suggestion in a drop down box, in the list you will recognize the word "melanoma".
Click on the suggestion you recognize "cancer melanoma" and you will get the research results for "cancer melanoma".