Burglary is entering any structure, or a locked car, with the intent to commit a theft or any felony inside.
It is a "wobbler," which means it can be charged as a felony or a misdemeanor. A felony carries a maximum sentence of three years in prison, and a misdemeanor can get you up to a year in jail.
As a first offender, you probably stand a good chance of avoiding the maximum sentences, but it's impossible to give you a meaningful answer without all the facts.
You need a lawyer to help you. If you can't afford to hire your own, the judge will appoint one for you at your first court appearance.
Robert Marshall is right, but I would add something: if the burglary is residential, it would not be a wobbler; instead, it would be charged as a straight felony with no provision to charge as a misdemeanor. Conviction could lead to time in state prison (2/4/6 years), but sometimes plea agreements in residential burglary cases can result in county jail time.
See Penal Code sections 459 (definition), 460 (degrees) and 461 (punishment), below.
459. Every person who enters any house, room, apartment, tenement, shop, warehouse, store, mill, barn, stable, outhouse or other building, tent, vessel, as defined in Section 21 of the Harbors and Navigation Code, floating home, as defined in subdivision (d) of Section 18075.55 of the Health and Safety Code, railroad car, locked or sealed cargo container, whether or not mounted on a vehicle, trailer coach, as defined in Section 635 of the Vehicle Code, any house car, as defined in Section 362 of the Vehicle Code, inhabited camper, as defined in Section 243 of the Vehicle Code, vehicle as defined by the Vehicle Code, when the doors are locked, aircraft as defined by Section 21012 of the Public Utilities Code, or mine or any underground portion thereof, with intent to commit grand or petit larceny or any felony is guilty of burglary. As used in this chapter, "inhabited" means currently being used for dwelling purposes, whether occupied or not. A house, trailer, vessel designed for habitation, or portion of a building is currently being used for dwelling purposes if, at the time of the burglary, it was not occupied solely because a natural or other disaster caused the occupants to leave the premises.
460. (a) Every burglary of an inhabited dwelling house, vessel, as defined in the Harbors and Navigation Code, which is inhabited and designed for habitation, floating home, as defined in subdivision (d) of Section 18075.55 of the Health and Safety Code, or trailer coach, as defined by the Vehicle Code, or the inhabited portion of any other building, is burglary of the first degree.
(b) All other kinds of burglary are of the second degree.
(c) This section shall not be construed to supersede or affect
Section 464 of the Penal Code.
461. Burglary is punishable as follows:
(a) Burglary in the first degree: by imprisonment in the state prison for two, four, or six years.
(b) Burglary in the second degree: by imprisonment in the county jail not exceeding one year or in the state prison.
As stated, you can face a substantial amount of time in State Prison. Its unlikely that will occur here because its your first offense. An aggressive defense could you a substantially reduced charge and/or sentence. Consult a Criminal Defense Attorney. Most of us give a free evaluation.