Drive: (in my humble opinion one of the best features included with your gmail account)
If you are new to Google you may not know that you are given 15Gb of space to save files. Let's say you have a pdf of some license you want to have available on another pc or your phone or tablet. Save the file to Google Drive and you can open it anywhere you sign in to your Google account! You can also "Share" that same file with others. You can limit their access to only "View" or you can give them total acces to edit the file.
Docs:
Sheets:
Meet:
Calendar:
Chat: