After a long search, I found the lyrics of this particular Bengali Song myself:
Fute Full Apon Shukhe...
Kaar isharai...
Kaar Adore...
Kaata Bon...
Shomirone Shohag Chorai..
And here is a (free) translation:
Flowers are blossoming encouraged by their own happiness
I wonder who is giving them the cue (to blossom)
I wonder at whose loving caresses
and the breeze spreads loving aodrations to the whole forest