The Condition screen allows you to define a condition. A condition consists of two or three parts. The first is the Operand. This is the object of the condition. The second is the Operation. This is action you wish to ask about the Operand. The third is the Argument. Depending on the selected Operation there can be zero, one, or more arguments applied to the condition.
Combined, the operand, operation, and any arguments is basically a question with a yes or no answer. If the answer is yes then the condition has been met. If the answer is no then the condition has not been met and doesn't apply.
You can create a condition with specific operation arguments or you can create a condition that results in you being prompted to provide a specific value when a filter is being applied. For example, you can create a condition such as "book genre is Fiction". But you may want to view books from other genres as well. It would be better to create the condition as "book genre is <prompt>". Then when you apply the filter you will be asked to pick a specific genre. This makes it easy to quickly see books of a specific genre without having to create a unique filter for each genre.
The Condition screen is in two main sections. The top section shows the currently selected operand, operation, and any arguments. Depending on which row in the upper section is selected, the bottom section displays a list of possible choices.