Question: why ravana has 10 heads?
Answer: was not born with 10 heads. Ravana performed an intense penance (tapasya) for several years to please and get a boon from Lord Brahma. During his penance, Ravana chopped off his head ten times as a sacrifice to please Lord Brahma. ... Thus Ravana got ten heads and twenty arms, due to which he is also known as "Dasamukha".