When soccer was first played in Brazil they only played with a ball made of cloth bunched together and wrapped in rope. Over the years it has evolved into a sport of jerseys, shin guards, cleats, and complex goals and balls.
All professional teams have jerseys, and all of them are different. Their most common purpose is to separate the teams so the referee can make the proper calls. They can be flashy, they can be cool, but they always carry their number on the back.
Shin guards are made to protect your shins as you might have imagined. You strap them on to the lower part of your leg.