What popper means by his theory of falsifiability is that a hypothesis can be put to the test and observed and proven wrong. There are specific parameters where a theory can be proven wrong by observation. He thinks that this distinguishes science from non science because non-science beliefs make ad hoc statements and allows the conclusions to go beyond the premises of a theory. He also thinks that theories can be falsifiable and not confirmed because there are other factors that could have contributed to the desired outcome that was observed. If it is not falsifiable, it is not a scientific theory.