external hard drive cloning, image, copying and with what?

Hello,

I have a 2 terabyte external hard drive that appears to be defective. As soon as I plug it into the PC, the contents are displayed, but when I click on something, it freezes. I've tried various cables, and I'm leaning towards a defective hard drive. Now I want to back up the data; there are various methods for doing this. Of course, I want to protect the read/write head as much as possible. The goal is to back up the contents, approximately 800 GB, on my laptop. Can I clone it at all, or does an empty hard drive need to be available? Will 2 terabytes be cloned, or just the 800 GB? Is creating an image sufficient? Which freeware is suitable for this? What tips can you give me?

Kind regards