In Hinduism, we have so many mantras for the many gods, the common man is completely bewildered. They are in Sanskrit, most are complex and hard to pronounce; we can only guess their meaning, or look for some trustworthy translations. Sri Purandara Dasa offers solace for us poor souls in this song. We do not need complex mantras for prayer. The name "Raama" - calling for Sri Raama (Sri Ram)- chanted with bhakthi (devotion) is all we need in this world.
Sri Hari's (Narayana) most kind and benevolent incarnation was Lord Sri Raama. Remembering and chanting his simple name is the medicine for all the evils in this world. Lord Shiva indicated as much to Parvati in the Vishnu Purana "sahasra naama tat tulyam Rama nama varanane" (the name of Lord Rama has the weight of- is equivalent to- the thousand names of Lord Vishnu (in Vishnu sahasra nama)).
There are many versions of this song on Youtube. A beautiful rendering of the song by Sri Vidya Bhusana is below. Note that there are slight variations in the various versions of the song online. (This is true of almost every song).
Rama mantrava = the (holy) mantra of Rama's name, japiso = do japa of (i.e. chant in complete devotion), hey manuja = hey man (or woman) "Manuja" refers to "one born of Manu", a human being
Meaning: Hello my fellow man (woman), chant the mantra (name) of Rama with devotion!
Aa mantra ee mantra necchhi nee kedabeda
Somashekhara thanna satige pelida mantra
Aa = that, mantra, ee = this, mantra, nechhi = believe, nee = you, kedabeda = don't be fooled
Somashekhara = Lord Shiva, thanna satige = to his wife, pelida = told, mantra
Meaning: Do not be fooled by this or that mantra. Follow the holy (Rama) mantra which was recommended by Lord Shiva Himself to his wife (Parvati).
Kulahinanaadaru koogi heLuva mantra,
Jalajapani nithya japisuva mantra,
Kulahinanaadaru = even if one is without religion, koogi heLuva = shout loudly, mantra,
Jalajapani = Lakshmi devi (jalaja = the flower born of jala, water- the lotus flower), pani = one holding a lotus, Lakshmi Devi) nithya = everyday, japisuva = chanting, mantra
Meaning: The Rama mantra can be shouted- chanted loudly- by even someone without any religion or creed. (Perhaps Sri Purandara Dasa is alluding to rishi Valmiki who was a wild hunter in the forest before he was inroduced to Rama mantra by sage Narada). Sri Lakshmi devi herself chants this mantra everyday.
Kalusha parvatakidu kulisha vaagiha mantra,
Sulabhadindali moksha sooregombuva mantra
Kalusha parvata = mountain of sin (paap), kulishaevaagiha = (is) a weapon to destroy, mantra,
Sulabhadindali = easily, moksha = salvation, sooregombuva = makes attainable, mantra
Meaning: The Rama mantra is the weapon that destroys the mountain of sin which is a part of this life. And it makes salvation easily attainable to everyone. (How great is the Rama mantra!)
Snana mounangaLige sadhanada mantra,
JnanigaLu manadi dhyanipa mantra
Snana mounangaLige = for taking a bath (to purify oneself) or for silent medidation,
sadhanada = vehicle for, mantra, Jnanigalu = the learned people (jnanis), manadi = in their
mind, dhyanipa = meditate upon, mantra
Meaning: The Rama mantra is a vehicle for meditation and purifying oneself. It is also the mantra medidated upon by learned people.
HeenaguNangaLa hingisuva mantra,
Yenembe VibhishaNage pattakattida mantra
HeenaguNangaLa = (one's) bad qualities, hingisuva = suppresses (eliminates), mantra,
Yenembe = I can tell you (this), VibhishaNage = for VibhishNa, pattakattida = make (him) sit
on the throne (i.e. make emperor), mantra
Meaning: The Rama mantra eliminates one's bad qualities, and indeed it is the mantra that made VibhishaNa the emperor (in the Ramayana, after the killing of the demon Ravana).
Sakala vendangaLige saaravenipa mantra,
Mukuthi margake ide moola mantra,
Sakala = all, vedangaLige = vedas, saaravenipa = the essential meaning of, mantra,
Mukuthi margake = the path for mukthi (salvation), ide = this, moola = root, mantra
Meaning: The Rama mantra encapsulates the essential teaching of the Vedas (the supremeness of Sri Hari). It is the root mantra for attaining salvation.
Bhakuthi rasake batte omme thoruva mantra,
Sukhanidhi Purandara Vittalana maha mantra
Bhakuthi rasake = the essence of Bhakthi (devotion), batte = path, omme = at once, thoruva =
points to, mantra, Sukhanidhi = the source of bountiful happiness, (is) Purandara, Vittalana =
Vittala's, maha = great, mantra
Meaning: The Rama mantra is path to the essence of Bhakthi (devotion), and it is the great mantra of Sri Purandara Vittala (Sri Hari), the source of all happiness.