At the moment, every free Google account comes with 15 GB of online storage for all your Gmail, Drive and Photos needs. Email and the files you store in Drive already counted against those 15 GB, but from June 1, all Docs, Sheets, Slides, Drawings, Forms or Jamboard files will count against the free storage as well.
Those tend to be small files, but virtually all of your Google Photos uploads will now count against those 15 GB as well.