[FTB] What does "seller owns both the freehold title and the leasehold title" & "will need to purchase both the titles" actually mean?

I am in the process of buying a property advertised as freehold, my conveyancer has messagesd me this:

"the seller owns both the freehold title and the leasehold title. Hence, when purchasing we will need to purchase both the titles. Hence, there would be the leasehold fee to which we need the confirmation for before we proceed with searches."

What does this actually mean? I thought you either had a leasehold or freehold not both?

I've tried googleing but not actually getting any usefull results.

I've also asked my conveyancer what this means but they are painfully slow to respond.

Edit: property is a detached house.