Simplify the following text for a Grade 6 native English-speaking person.
Original: Hindus believe that there are periods of time called yugas ( `` ages '' or `` eras '' ) : Satya Yuga , Treta Yuga , Dvapara Yuga , and Kali Yuga . When Kali Yuga ends , a new Satya Yuga begins .
Simplified: These are the Krita Yuga , the Treta Yuga , the Dvapara Yuga , and finally the Kali Yuga .