Gayathri Manthra

: Om bhur bhuvah svah tat savitur vareṇyaṃ bhargo devasya dhīmahi dhiyo yó naḥ pracodayāt

In Devanagari: ॐ भूर्भुवः॒ स्वः॒ । तत्स॑वितुर्वरे॑ण्यम् । भ॒र्गो॑ दे॒वस्य॑ धीमहि। । धियो॒ यो नः॑ प्रचो॒दया॑त्॥ ।

Gayathri Manthra is from Rigveda and believed to be written by Rishi Viswamithra . This manthra is important for Upanayanam ceremony for Brahmin boys. 

The meaning of Gayathri Manthra

"May we attain that excellent glory of Savitar the god:

 So may he stimulate our prayers."

 Word by Word meaning of Gayathri Manthra

 dhīmahi "may we attain"

 tat vareṇiyam bharghas '"that excellent glory" (accusatives of tad (pronoun),

 varenya- 'excellent' and bhargas- 'radiance, splendour, glory')

 savitur devasya "of the lord savitar " (genitives of savitr-, 'stimulator; name of a sun-deity' and deva- 'god, deity')

 yaḥ prachodayat "who has the ability to encourage"

 dhiyaḥ naḥ "our prayers"

 This manthra was translated by Swami Vivekanda  as below

"We meditate on the glory of that Being who has

 Dr. S. Radhakrishnan’s Traslation  is below

1."We meditate on the effulgent glory of the divine Light; may he inspire our understanding."

 2."We meditate on the adorable glory of the radiant sun; may he inspire our intelligence."