Trello is a tool for tracking workflow. You create a series of cards that you move between boards. Each card can be assigned an person and/or a label.

In order to filter you simply press the letter ‘f’ on your keyboard when you on the Trello page. This brings up a menu to the right showing all the labels and people you can filter on.

I do feel ridiculous writing something so simple but it took me so long to find out how to do it, and I dont want to forget.