Single Value Column. When you enter the search term and it’s written to the user specific column, it’s only written to a single row. But you want to filter across all rows, so you need the search term applied to all rows. The single value column does this for you.
It’s used as part of each condition in the if-then-else column. So for each column that you want to apply the search to, you’ll have a separate conditional in the if-then-else that compares the value in that column to the value in the single value column. You’ll probably want to use “if column-to-be-searched includes single-value-column, then true”. The effect of that is that if any of the columns you apply it to include the search term, then it will return true, and the associated row can be included in your search results.