# How exactly dependent variable is expressed in terms of independent variables using Partial Least Square Regression Method?

I understand the working of NIPALS algorithm but while doing the regression using PLS how exactly the relation between known and unknown is established using Principle Component Analysis. The idea is clear up to the points both dependent and independent are expressed in form of their principle components. After I am not able to understand.

PS: I have read text and some papers about it but they are very difficult to understand. This Question may sound a trivial one, but please bear with me. Correct me if I am wrong.