It depends on what the files are. Extensions aren't very important in Linux (which is the underlying OS in Android) so, unlike Windows, where an .exe is an executable file, a .bin file in your phone could be whatever the app that created it means it to be, maybe human-readable, maybe not.
If it's a binary file, though (the most common use for the .bin extension), it's not a human-readable file, like text or a picture, it's machine code and even if you could open it, it wouldn't make any sense to you. It would just be a long string of values, meaningful to some app that uses it.