A California Notary Public is a person of required honesty, credibility, truthfulness and integrity appointed by the State of California to serve the public as an impartial witness in performing a variety of acts related to the signing of important documents, taking oaths and affirmations and performing other acts authorized by law (GC 8201.1 and 8205).
When a Notary notarizes for a signer, the Notary's job as an impartial witness is to do certain things such as authenticate a person's identity and verify that the person signed the document.
A Notary Public is an official whose purpose is to serve the public in an unbiased manner. The Notary's right to act as an official witness is granted through a written authorization call a "commission" which must be renewed every four years. A California Notary Public's jurisdiction is statewide.
Ref: National Notary Association Reference Guide
A California Notary Public is not allowed to give legal advice.