Picturised on: Katrina Kaif
Bahut hui hai ye aankh micholi,
aaj khelungi main ras ki holi,
ras ki holi, ras ki holi..
Now that's enough of this hide and seek,
Today I'll play holi with rasa..
holi with rasa, holi with rasa..
Here the thing is that ras is a word with two meanings, one is juice, and the other one is a concept that for lack of a better word you can say joy. So here she's talking about the mango juice, while it also means she'd play Holi with joy.
Holi is an Indian festival where people throw colors and colored water over one-another.