This particular guru purnima prayer is known as ashtakan and it is a popular prayer dedicated to guru it is chanted to get the blessing of guru.
(PRAYER AND ITS MEANING)
Guru Devo Maheshwara
Guru Sakshat Parabrahma
Tsmai Shri Guruve Namaha
The teacher is like Lord Brahma as he Generates the knowledge within us,
like Lord Vishnu as he Operates the ideas/knowledge
in our mind unto the right path,
and like Lord Mahesha (Shiva) as he Destroys the wrong concepts attached to our knowledge, while enlightening us on the desired path.
Thus the teacher is like our ultimate God and we should pray and give respect to our teacher.