Where can I see the actual values for standard deviation/standard error that Prism plots as error bars?

Prism computes the values internally, but it doesn't show them to you. If you want to see the SD or SEM values:

1. Go to the data table.
2. Click analyze.
3. If you have a XY or Grouped table: Choose "Row means/totals".
   If you have a column table: Choose  "Column statistics".
4. Choose options on the dialog and click OK.

If you entered survival data, the survival analysis results are probably already present in your project. Go to that results sheet, and view the table of survival proportions, which includes standard errors or confidence intervals. If you have a contingency or parts of whole table, the concept of SD or SEM of the data doesn't really make sense.