A California Civil Code 1542 waiver is a standard ptovision lawyers put in settlement agreements to end the dispute forever. It means you're waiving claims you don't know about, even if you find out about them after you sign. The waiver doesn't affect what the company has agreed in the agreement to give you, such as these payments for 9 more months. It's risky to sign something you don't fully understand, so perhaps best to have this document reviewed by a lawyer before you sign it.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.