In their continuing effort to AI all the things, Google announced at Google Cloud Next yesterday that grammar suggestions will be rolling out to Google Docs in the near future. The Mountain View company has already opened up the Early Adopters Program signup for those who are on G Suite and want to give it a try.
The feature works as you would expect and is similar to other tools provided by other apps, most notably Microsoft Word in Office 365. When you have a word or phrase that grammatically needs to be improved, it will be underlined in blue. You can then click on it and get the suggestion for improvement and either accept it or reject it.