The Logic Block provides you with tasks that are based on logical actions. You have here the Branch task, Delay task, Compute Task, and JSCode
So in this example, the JS Code block would contain a certain code that gets the Taxable Amount as the input value. Taxable amount is derived as Quantity * Price.
In this example, we have included the compute block to set values for the tax and the total invoice amount which would then be used in the PDF Creator configuration.
The JS Code task will be a part of the Action flow components with values computed used in different actions.
The invoice would be generated as seen in the preview below with the tax amount displayed accordingly.