Imagine you want to say something in English and there are two different ways of expressing your idea but you don't know which to choose. If you check Google Ngrams, you'll be able to see which expression is most frequent. This might help you to make your decision.
Think about the following questions and try to find the answers on Google Ngram Viewer.
Do we tend to say 'I started' or 'I have started'?
Do English speakers say 'half a year' or 'six months'?
Do English speakers prefer to say 'recently' or 'lately'?
Click here to find out the answers. Google Ngram will give you some basic frequency information. An English teacher might be able to provide an explanation about why some words and phrases are more popular than others.