Finder froze when copying large folder

I have a 1TB hard drive which I need to backup the info, so I copied all folders into another drive (4 TB) and after a full day of copying progress the Finder appears this way:

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So it says “About 5 seconds remaining…” and the actual free size of the 4TB drive tells me the files are there, but as you can see in the picture most of the folders are greyed out, like if they were not there.

I want to know what can I do, someone knows what happens if I cancel the transfer?