To add or replace text in cells in a table with values you can use the filter for "Fill Cells with", this can be found under the Refine Cell Values option.
Once selected there are a couple of options that can be used to determine the value of the cell in the column of your choosing. These are as follows:
Set text of cell - This will replace any values found in the column with the typed-in value
Add text to cell - This will append the typed-in value into the cell at the beginning or end.
If you are looking to set a value for only blank cells in a table please see our article "How to use the filter for "Fill Empty Cells with"