Section 1946.2 changes the default rule that a periodic tenancy can be ended without giving a reason. Once a tenant has continuously and lawfully occupied residential real property for 12 months — 24 months in the case where additional adult tenants were added to the lease before the first tenant reached 24 months — the owner may not terminate without just cause, and the cause has to be stated in the written notice itself. A notice that gives no reason, or gives a reason not on the statutory list, is not a notice that complies with this section.
The section then divides the grounds in two, and the difference decides who pays. "At-fault just cause" in subdivision (b)(1) covers non-payment of rent, breach of a material lease term after written notice to correct, nuisance, waste, refusing to sign a similar renewal, criminal activity, unlawful subletting, refusing lawful entry under § 1954, and unlawful use of the premises. "No-fault just cause" in subdivision (b)(2) covers the owner or a close relative moving in, withdrawal of the unit from the rental market, compliance with a government order or local ordinance requiring the unit be vacated, and demolition or substantial remodel. For the at-fault grounds resting on a curable breach, the owner must first give the tenant a chance to cure. For the no-fault grounds, the owner owes relocation assistance — one month's rent, paid or waived — and a notice that says so.
Subdivision (e) lists the housing the section does not apply to, and it tracks the exemption list of § 1947.12 closely: new construction, single-family homes and condominiums with the required exemption notice, owner-occupied duplexes, owner-occupied single rooms, dormitories, transient occupancy, and housing already under a stricter local just cause ordinance. Whether a stated reason is genuine, whether a remodel is "substantial", and whether a relocation payment was properly made are questions of fact and local rule, and are the point at which to get advice rather than to rely on the text alone.