The filter action: Alteryx's answer to refining one's data into more manageable, and coherent formats to become (in theory) more useable. This is achieved by filtering your data with a condition, upon which the outputted data can be returned.
For example, the data above shows the sales data from various pet related businesses. I would like to only see the shops which have a sales value of greater than 150,000 in January. In order to do this I could use the filter tool!
It is as simple as it looks. By selecting the field name you require to filter the results by and inputting the value of results that you would like be to returned, the outputted data has returned shops which have sold a total of over 150,000 (of arbitrary currency) for January!
Although this is a very simple example of how the filter action works, it serves to show its basic functionality and the context in which one would use this tool.