The "Clipboard" is an internal use of the Mac's memory that temporarily hold data that you copy from a source. It isn't accessible other than to paste that data to another location in a document or file or folder.
Any time you invoke the "Copy" command, the selected object (text, file, folder, pic, vid, whatever you selected) is stored in memory on this "clipboard". When you invoke the Paste function, that info stored on the clipboard is pasted to the location you have specified.
Objects copied to the clipboard remain there until you copy something else or shut down the computer. Thus you can paste the same data several times to different locations.
As you have questions about how to use your computer, the macOS User Guide is always available on your Mac by clicking in the Finder menu bar > Help > macOS Help. You can also find it here: macOS User Guide