Onedrive is cloud storage that provides synchronisation between the onedrive directory on your PC and a cloud based copy. It's accessible from any device that you log into your Microsoft account on, it's not linked to a specific machine. You can specify whether everything in the onedrive folder is physically stored on your PC as well as being duplicated in the cloud or, to save hard drive space, have the files only stored in the cloud and synchronised with your device when you want to open them.
Although Onedrive is a Microsoft thing it works just fine with Apple devices in the same way that Dropbox etc does. If you're getting problems I suggest you take a look at your Onedrive settings.