You may don’t know what means ‘files on demand’ with the OneDrive/OneDrive for Business client.
This is the functionality which used to be available with the OneDrive client back in the Windows 8.x years. This feature allows you to not synchronize a folder/file in your client but was still displayed in the Windows Explorer. This feature (for some reasons) has since being retired which generates lot of requests/complaints.
So good news, Files on Demand is back by popular demand 
It has been announced at the Build 2017 conference earlier last week and it will be delivered with the Windows 10 Fall Creators update.
