This "Hidden Column" and "Added column for filtered items" showed up out of nowhere

[Juan Carlos Gonzalez]

One day i opened my dashboard and this columns where there. I don't know where they came from, but i would like to know how to do it intentionally. Specially the "Hidden Column" is a good thing to know because it is not hidden in the Data Canvas but it is in the user interface

[Fredrik Rosell]

Hello!

For the first type - "Added column for filtered items" - that was likely created when (someone) filtered on marked rows.  

Example:

1. Mark some rows.

2. Edit menu > Marked Rows > "Filter To"

Regarding hidden (data table) columns, one way of getting that is if you delete a column that is used to calculate other columns. When attempting to delete it you will be prompted if you want to hide it instead, to avoid breaking the calculation. If you delete that hidden operation in the data canvas, that unhides the column.