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A lease is a legal document, but can be a verbal arrangement, which confers a right on one person (called a tenant or lessee) to possess property belonging to another person (called a landlord or lessor) to the exclusion of the owner landlord. The relationship between the tenant and the landlord is called a tenancy, and can be for a fixed or an indefinite period of time (called the term of the lease). The consideration for the lease is called rent.
Under normal circumstances, an owner of property is at liberty to do what they want with their property, including destroy it or hand over possession of the property to a tenant. However, if the owner has surrendered possession to another (ie the tenant) then any interference with the quiet enjoyment of the property by the tenant in lawful possession is unlawful.
Similar principles apply to real property as well as to personal property, though the terminology would be different. Similar principles apply to sub-leasing, that is the leasing by a tenant in possession to a sub-tenant. The right to sub-lease can be expressly prohibited by the main lease.