What the hell is a bail bond?

I have been charged with retail theft (less than $25 worth of items) and lying to the police about my information (obstructing theft). I am 20 and I live in Illinois. Last night I was taken down to the station after getting caught shoplifting, and they charged me with those two misdemeanors. They told me that the bail bond for the offenses has been set at $1500. What does this mean exactly? I wasn't sent to jail or anything. I have court in a month. Does this mean I am going to jail if I plead guilty? I have never been charged with retail theft before, but have been arrested for a small misconduct back when I was 16. Other than that my record was clean until last night. I am very worried of what's going to happen, and currently I have no job and can't afford an attorney. And I do not want my parents to find out about this, because I will surely get kicked out of the house. I am very sorry and truly regret what I have done. I just want another chance. So please help me out here instead of saying you're stupid or something, b/c I understand what i did was very very stupid.