Breaks down into: lender fees (origination, underwriting), third-party fees (appraisal, credit report, title insurance, escrow, recording), prepaids (first year of homeowners insurance, first few months of property tax reserves, prorated interest), and taxes (California property transfer tax).
Typical Southern California closing costs on a $750K purchase run $15K–$25K depending on loan program and negotiated concessions.
Seller credits (up to 3–6% depending on down payment and occupancy) can offset part of the closing costs — an important negotiation tool especially in buyer's markets. Your broker should tell you the maximum allowable credit for your scenario.