A hypothesis is a suggested explanation for a phenomena, based upon a conceptual “working model” of how a system works.
Good hypotheses generate predictions that can be tested.
In experimental sciences, experiments are set up to test the hypothesis.
In the historical sciences, additional evidence is gathered in the place of experiments (although not nearly as incisive, some areas do not easily lend themselves to experiments (i.e., stellar astronomy)).
If the predictions of the hypothesis are not borne out, the hypothesis is falsified.