The UK, for historic reasons, doesn’t believe in private property for the common man; almost all property in the form of land belongs to the government or someone with a legacy from the ruling class of nobility. Thus most homeowners don’t own the land their home is on, they just own a very long term lease from the actual landowner (not sure precisely what is customary these days, but imagine a 99-year lease) with N decades left on it. This is a leasehold.

Owning the land is called a freehold, and the owners are called freeholders instead of leaseholders.

Contrast the US where a lease of a home is typically paid monthly and contracted on a year to year basis.