Aum Trayambakam Yajamahe,
Sugandhim Pushtivardhanam;
Urva Rukamiva Bandhanaan,
Mrityor Mokshiye Maamritat.

ॐ त्रियम्बकं यजामहे, सुगन्धिं पुष्टिवर्धनं
उर्वारुकमिव बन्धनान् मृत्योर्मोक्षिय मामृतात्

OM triyambakam yajāmahe sugandhim pushTivardhanam,
urvārukamiva bandhanān mrrityormokshiya māmrritāt.

Summary of the Maha Mrityunjaya Mantra

We worship Shiva - The Three-Eyed (tryambakam) Lord (yajamahe);
Who is fragrant (sugandhim) and nourishes (pushti) and grows (vardhanam) all beings.
As the ripened cucumber (urvarukamiva) is automatically liberated (bandhanaan) (by the intervention of the "farmer") from its bondage to the creeper when it fully ripens;
May He liberate us (mokshiya) from death (mrityor), for the sake of immortality (maamritaat).

We pray to Lord Shiva whose eyes are the Sun, Moon and Fire
May He protect us from all disease, poverty and fear
And bless us with prosperity, longevity and good health.

The Maha Mrityunjaya Mantra is a prayer to Lord Shiva (part of the hindu trinity, the lord of destruction, penance and meditation) for help in overcoming "death". The seeker is more concerned with avoiding spiritual "death" rather than physical "death". The mantra is a request to Lord Shiva to lead us to the mountain of meditation, which is indeed Lord Shiva's abode.
Legend has it that Lord Shiva appeared before his devotee Markandeya (who was destined to die at the age of sixteen) and stopped his aging process a few days before he was supposed to turn sixteen. Thus, death would never be able to claim him! Hence, this mantra is also referred to as the Markandeya mantra in classical hindu studies. The mantra should ideally be repeated 108 times, twice daily, at dawn and at dusk. It is particularly useful for meditation and yoga practice.