When entering data into tables formatted for XY or Grouped data, replicates go into side-by-side subcolumns. Prism then can plot these individually, or plot mean and error bar.
You can also format the table to enter mean, SD or SEM, and N. This is useful if you have already averaged the data in another program or if you have more than 52 replicates. Otherwise, it is best to enter the raw data into Prism, so you can plot every replicate.
Prism can take your raw data, and create graphs with mean (or median) and error bars (defined in several ways). There is no need to run an analysis to compute the SD or SEM. But if you want to see the descriptive stats for each set of replicates, use the Row Means and Totals analysis.