Sure.
For the List Boxes:
Use your list as an input. Since we know that it outputs a string of True/False, rather than try to parse that all out we just put the results into a text box. Then, we use parse out the comma separated values into separate lines and the True/False into separate columns. This allows us to filter and gives us just what we need next: a list of the names to keep.
In the case of the first List box (tool 3), we know that we need to use that to select rows. Since we've already parse out the True/False statement and have the names as a single column, we can use that to join on the input data.
In the case of the second List Box (tool 139), we need that to select columns. But rather than work through some fancy logic, we already know that that Union tool as the ability to limit results on common columns. So, we pivot the list into columns using a Crosstab tool. Add in a dummy field (Customer Segment) for the field we need but isn't part of the list from 139. Limiting the number of rows to zero, is the same thing as only passing a schema - or in this case selecting the columns for output.
Hope that makes sense.
How can you practice?
Just keep using Alteryx. Find reasons to use it. Find problems to solve with it.
The Community is a great place to find new problems to solve. There are weekly challenges as well as the questions here like you posted.
Don't be afraid to try something. You won't break it, so you have nothing to lose by just trying.
