The p value is the probability of calculating a test statisitc value equal to or greater than the result obtained from the sample data when the null hypothesis is really ture. In other words, the p value is the smallest level of significance at which the null hypothesis can be rejected fo a given dataset. The choice of statistical test is in part determined by the design of the study and the type of data that is collected. Here there are only two choices and there are no intermediates possible. On the other hand, data on the number of offspring a group of females produce is a type of numerical data because the answer is a number.
Numerical data can be discrete or continuous .
The number of cars owned is discrete because there are a finite number of interger responses. You can't own half a car. Height on the other hand, in continuous because it can take on any value within a range or interval depending on the precision of the measuring device. Catagorical data are measured using either a nominal or ordinal scale. Interval and ratio scales of measurement are numerical but differ in one important feature.