Content URIs are not (necessarily) file system paths. They are a representation defined by the content providers to serve data to whoever requests it without revealing the actual source of data, in a way. 
The Content URI's are generally in the following form :
content://authority/path/id
Where
content - the first part (here content) is the scheme of the URI. It could be anything like file for File Uri's.
authority - The name of the content provider , i.e. the content provider uses this part to identify content uri's meant for them and not for some other content provider.
path & id - these are defined by the content providers to (generally) identify the exact location of data in their data store (local database, some rest api etc)
Interestingly, Content providers provide a way to get a hold of an InputStream for the content represented by a ContentURI - using getContentResolver().openInputStream(uri)
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