Apple Numbers help

It is hard to tell from here how much or little experience someone has with spreadsheets. You mentioned Excel and you mentioned a feature that almost no beginner user would even know about, much less how to use it, so I assumed you were not a beginner with spreadsheets and would know about columns and math operations and simple formulas. Below are more detailed instructions

If your "whole column" is column B and you want to lower all your values by 5,

1. Add a new column next to B. Do this by right-clicking on the column letter B and choosing Add Column After. This will become column C. It may or may not be blank; doesn't matter.
2. In cell C1 put the formula =B1-5 and press Return
3. Select cell C1 and Copy (Command C)
4. Select the rest of the cells in column C. Paste (Command V). All cells in column C should now have a formula that applies to their row. For example, the formula in cell C5 should be =B5-5. All the results should be 5 less than what is in column B.
5. Select all the cells in column C
6. Copy
7. Select all the cells in column B
8. In the Edit menu is Paste Formula Results. Do that. Column B should now have the updated numbers.
9. Delete column C. Do this by right clicking on column letter C and choosing Delete Column.

It takes way less time to actually do all this than it does to write the instructions.

Numbers does not have that same "Paste Special" operation.

1. Add a temporary new column
2. Use formulas to change the numbers to what you want
3. Select the new numbers and Copy
4. Paste Formula Results back into the original column
5. Delete the temporary column.

If this is something you do frequently, an AppleScript can be written to do what "Paste Special" does with add/subtract/multiply/divide, versus going through these steps each time. Or maybe a change can be made to your spreadsheet so it does not require this to be done.