In your Oracle Linux guest VM, under the Virtual Box Devices ->Shared Clipboard menu option, you can select the bidirectional option to allow copy/paste between the host/guest operating systems. This should work if your Guest Additions software is installed properly.
Copying of the clipboard only works for applications that use a clipboard, which is typically a background application or built into the graphical window manager. In other words, you need to run your terminal session in a X Window terminal application. The text only console does not support the clipboard.