As a leaseholder you will own the lease to your home for a certain amount of time, but the freeholder will be the legal owner of the land that the building is situated on. At the end of a fixed term the property should go back to the freeholder.
You and your freeholder will have rights and obligations, which will usually be set out in the original lease. In cases of dispute, the courts may imply terms into a lease if considered necessary for the lease to be effective. Implied rights include:
Charges
Additional rights of long leaseholders
Problems with management of the property
Repairs
Forfeiture
This information is also available in Arabic, Farsi, Gujerati, Hindi, Polish, Punjabi, Urdu and Somali (pdf).