Reference:
https://help.salesforce.com/articleView?id=bi_dashboard_build_tips.htm&type=5

Reference:
https://help.salesforce.com/articleView?id=bi_limits.htm&type=5

* template-info.json manages all elements of your template, including metadata information about the template, the Analytics objects that define dashboards and lenses, and the other files that are part of the template. * ui.json manages the configuration wizard that drives app creation. It defines the number of wizard pages, the order of wizard questions, and any messages you want the user to see. * variables.json contains all template variables, including text for wizard questions and specifications for the answers. Variables also define conditional questions. For example, you may want some questions to appear in the wizard only if an org contains certain data. Or you might want to add more specific questions based on the answers to more general wizard questions. * template-to-app-rules.json defines the rules the template follows. For example, you could define a rule that specifies that if an org doesn't use certain Salesforce objects, the app won't refer to them in dashboards or include them in the dataflow. Rules also define how variables are handled. For example, if the wizard asks which fields to include in filters for accounts, template-to-app-rules.json determines how that choice is reflected in dashboards.