how to open clipboard on MacBook?

What is it you're trying to do?

The clipboard isn't usually directly accessible but, conceptually, you can 'see' what's on the clipboard by pasting it into a new document.

The main issue is that the clipboard often contains multiple layers of information, and applications can define both what they put on the clipboard, and what they paste from it.

For example, let's say you select a file in the Finder and 'copy' it.

The Finder doesn't necessarily copy the file itself, rather an alias (reference) to it.

When you paste that data, the result may vary depending on where you paste it.

If you paste into another Finder window, the Finder duplicates that file and makes a copy.

If you paste into an email message, Mail.app copies the file into the message body

If you paste into a text-based application (e.g. Terminal.app), the app pastes the path to the file

If you paste into other apps, you might just get the file name (no path)

So different results from the same clipboard contents.

That's why I ask specifically what it is you're trying to achieve.