OS licenses aren't "refurbished".
They are either "new never used", or "has been installed on something before"
Where did you obtain this?
I suspect they mean a key attached to a refurbished system.
Typically, those keys are not able to be re-appropriated for other systems, OP. Sometimes they're not actually even legit on the refurb, depending on how morally flexible the seller was. You would need a Windows 10 retail key, as I've never known refurbishers to use a transferable key.
Shame on them for even selling you that license. I've read up on the refurbisher professional, and they usually get those at a stop discount and they are supposed to go through a whole checklist to make sure a computer even qualifies as refurbished. Selling stuff that way is a good way to get in hot water, as selling licenses that way could be considered piracy.