Please help me understand my textbooks definition of probability level

This is my textbooks definition of probability level (p-value): a number, calculated with statistical techniques, that tells researchers how likely it is that the results of their experiment occurred by chance and not because of the independent variable(s); the convention in science, including social psychology, is to consider results significant (trustworthy) if the probability level is less than 5 in 100 that the results might be attributable to chance factors and not the independent variables studied.

This is the part I am confused about: the convention in science, including social psychology, is to consider results significant (trustworthy) if the probability level is less than 5 in 100 that the results might be attributable to chance factors and not the independent variables studied

It says to consider results significant or trusthworthy if the probability level is less than 5 in 100 but then says that those results could be attributable to chance factors and NOT the independent variable. Wouldn't that make the results insignificant or not trustworthy?