what is heisenberg uncertainity principle

Heisenberg's Uncertainty Principle is a consequence of what we call the Quantum Mechanical model. It states that there exist pairs of variables (measurable quantities) for which the product of ther uncertainties (errors in their measurements) are a constant.
Two of these pairs are, for example, energy and time, and position and momentum. The consequence of this principle is that trying to measure with greater accuracy of a pair of these variables will necessarily result in a greater error in the determination of the other. The classic example is the following: Suppose you want to determine the position of an electron. You could do so by shooting a photon at it and having it be absorved bby the electron. The absence of the photon on the other side would let you determine the position of the electron. But if you want to make your measurement more exact you would have to use photons of a smaller wave length which implyies higher frecuency and thus more momentum. Since the idea is for the photon to be absorved by the electron, you are changing the momentum of the electron. So you are increasing the uncertainty in its momentum. The Principle comes directly out of Shroedinger's Equation. I hope this helps!

Moreover, giving equations here wouoldn’t help. Considering that you must have already gone through them in your textbook. If not, then first go through it.