It's in a special area of the phone's RAM set aside as the clipboard. The only ways you can "access" it are copying, cutting and pasting. So if it's text, find something that accepts text (even a text editor or an email you're writing), long-press, and you should get a "Copy" button to press. Remember, only the last thing put into the clipboard is the one in it (in most devices - Samsung may - depending on the model - have a multi-clipboard).
If you want a multi-clipboard, and your tab doesn't have it, install
Clipper - Clipboard Manager, then you'll have a choice of things you copied or cut that you can paste. But, again, the "clipboard" is inside the app, it's not accessible by any other means. (And if you restart the device, or turn it off, anything in the clipboard gets lost, with the native clipboard or with most clipboard managers.)