Ratti Bhar ka jag saara meaning (Ra.One)

Ratti was a small unit of measurement of weight which is still used informally for weighing of jewels sometimes. Coming from that, 'ratti bhar' is a common phrase which means a very little, a rather insignificant amount.

Hence, the line ratti bhar ka jag saara in the song Dildara means that the whole world is hardly of any significance, when compared to his beloved.