The workspace can essentially change the commands and the types of commands that you see in the ribbon. You can change it according to what type of work you are doing and which commands are more useful than others. By default, it is set on the 3d basics type where basic 3d modeling and sketching commands are directly accessible to be of ease of use. If the workspace option is not visible in the quick access toolbar, click on the little arrow on the quick access toolbar and make sure there is a right before the workspace.
You can customize the workspace according to your liking, it is not necessary to use one of the default three options available but they provide a good base to whatever type of work you need to do. Customize by clicking on the workspace button and clicking customize. The window will open as shown.
This window will help edit existing workspace and set the ribbon and position the commands as you like (though it is recommended to not change too much in the beginning as the default workspaces have pretty much got it covered for you).
Also, save this new workspace with new name to get back to it whenever you like after pressing OK. To save just go to workspaces in quick access bar and click ‘Save Current As’.