What is the hyphotesis purpose?

An hypothesis, is of lower 'quality' than a thesis (aka a theory). 'Hypo' means before or earlier or above.

An hypothesis is the gist of a query that may be untenable, or it may prove out a good field for study. I may hypothesize that it rains more frequently on a Monday. When I have collected the data, from reliable sources, I may then examine the validity of the hypothesis, and compare Monday rain frequency (or intensity) against 'other day' rain frequency. The hypothesis helps us formulate the method of the examination, the controls, and so on.