In Australia, it's 16 and a half to start obtaining a license. We then have to go through our "plates" starting from learner, red provisionals, green provisionals then our full license.
Adding on Hero, some of it is general knowledge. Study what the road signs and markings do in your country. If you struggle, it's good to ask someone you know with their full license or check out the internet. Also observe what the driver does during a journey in the car as your testing officer will check you on this as you are being marked. These may affect your result.
I'm not sure about the age where you can begin obtaining your drivers license, but since you're 15, you should have enough time to study.
I wish you luck in the future!