It translates roughly to:
"When I saw you, I knew, my love."
Let's break down the phrase:
* Tujhe dekha: This means "I saw you".
* Tu yeh jana: This means "I knew this" or "I realized this".
* Sanam: This is a word for "lover" or "beloved".
The phrase is an expression of sudden, powerful love at first sight. It conveys the feeling of knowing instantly that the person you've just met is the one for you.
It's a romantic and poetic line that has resonated with many people and become iconic in Indian cinema.