All Hindus know about Ravana.
What do the 10 heads of Ravana signify?
One of the interesting answers could be found in the book Asura: Tale of the Vanquished: The Story of Ravana and His People:
Why is Ravana portrayed as ten-faced?
While the ten-headed, twenty-armed figure of Ravana as the supreme anti-hero, is familiar to every Indian and scholars of Indian mythology, few really know why he is portrayed in this manner. Traditonal Indian wisdom places importance on the control of one’s emotions and projectsthe intellect alone, as being supreme. The great King Mahabali, advises Ravana to shun the other nine base emotions of anger, pride, jealousy, happiness, sadness, fear, selfishness, passion, and ambition. Intellect alone is to be revered. Indian spiritual gurus have always stressed the need to overcome the Self and have considered these emotions detrimental to the elevation of the soul.
But, in his reponse to Mahabali, Ravana justifies and exults in the possession of all these ten facets, as they make him a complete man. Mythology thus portrays Ravana as Dasamukha, or the ten-faced one, while his twenty hands denote prowess and power. Ravana sees himself as the epitome of a complete human being, without any pretense to holiness or restricted by social and religious norms. He is as good or as bad as any human being, and as nature intended man to be. Society is unable to curb his other nine faces, as it does in the figure of Rama. So Rama may be seen as God, but Ravana is the more complete man.
Ravana, one of the most powerful beings ever to roam the earth is also known as the supreme anti-hero in Ramayana. He was the king of Rakshasas and is depicted with 10 heads and 20 arms, giving him the name of (10 faced) or (10 headed). He was born to Sage Vishravan and Asura mother Kaikashi.
Ravana's 10 heads symbolize the 6 Shastras and 4 Vedas, making him a great scholar and the most intelligent person of his time. He was a master of 64 types of knowledge and all arts of weaponry. A highly learned Brahmin, Ravana has to his credit over a dozen of texts of which Arkaprakasha, Kumaratantra, Indrajala, Prakrata Kamadhenu, Prakrata Lankeshvara, Ravana Samhita, Rigveda Bhashya, Ravanabheta, Krishna Yajur Veda etc. are some of the best known. He is known to have compiled Sama Veda with the relevant musical svaras (notes) and his Shiva Tandava Stotra is yet the most popular hymn ever sung in praise of Lord Shiva. His ten heads thus stood for this multiplicity of his genius.
Another negative interpretation of Ravana's 10 heads are the 10 emotions or senses in a human:
Manas (the mind)
Hindu traditions emphasize on the importance of controlling one's senses and projecting just the intellect alone, which is considered supreme over others. The use of other emotions are considered to be detrimental to the growth of a soul. The great king Mahabali advised Ravana to shun these nine emotions and to keep only intellect to which Ravana justifies that the possession of all these facets are equally important and make him a complete man.
The head controls our destiny and the ten 10 heads of Ravana controlled his actions which ultimately let to his destruction. The king of Lanka became a slave to his senses and since he could not control his desires, he not only destroyed himself and his clan but the whole Lanka was reduced to ashes as well. Having all this knowledge and not being unable to harness his powers was one of Ravana's biggest regrets as he lay dying on his deathbed.
Actually, if anyone deeply analyses the end of Lanka Kand of the original Sanskrit scripture of Ramayana (not any translations, even old ones), there's logical proof that Uttar Kand itself is an interpolated chapter of this great epic. But, I'm NOT saying that the relevant chapter is invalid, its just scripted/added later. Interpolation does not necessarily means its void or useless. 90% of the Purans more-or-less have interpolations.
Secondly, there's ample logical proof in the Sanskrit scriptures of Sundar Kand (10th Canto) and even in Arayanna Kand (49th Canto) itself, that Ravana did NOT had 10 heads and more than 2 arms!
Those are all imaginations of the later poets/pundits/translators! ;-)
(Everybody asks for sources/references and ultimately lands up in some translated editions/versions. My question is, how much expert are you in Sanskrit, leave aside any other ancient languages like Prakrit? Having Sanskrit as a third language in schools doesn't make someone an expert. Even so-called Sanskrit Pundits of today make lots of mistakes, both accidentally & purposely).