The number of resamples is the number of times Minitab takes a random sample with replacement from your original data set. Usually, a large number of resamples works best.
Minitab adjusts the data so that the center of the resamples is the same as the hypothesized proportion. The sample size for each resample is equal to the sample size of the original data set. The number of resamples equals the number of observations on the histogram.