The meaning of freehold property (usually a house) is that it’s bought and sold free and clear. The buyer owns both the property itself and the land upon which it stands, with no time limit or charges attached.
A leasehold property (usually a flat) is one which is bought only for a set period of time. During that time, an annual ‘ground rent’ must typically be paid to the leaseholder, sometimes just a few pounds, but often increasing over time to many thousands.
When the lease runs out, the property is forfeited back to the landlord – although in reality this rarely happens, because leases can be extended.