You could find the one metric that your team needs. To find this one metric depends on the stage you are at with your product and requires some digging to expose a data-point that is globally illuminating. Early stage products might look at daily active users, but later products may look at something more specific, like how many users completed X number of actions.
Acknowledging first the common adage that data (knowledge) is power, Evgeny Lazarenko goes on to break down some of the key metrics that you should follow as a product manager. These he groups by user engagement, business, and customer service.
Before its decided what you should be measuring and how, its useful to contemplate on what analytics are in the first place. Martin from Cleverism has done the hard work by looking at 1) analytics definitions, 2) key concepts of analytics, 3) main uses of analytics in product management, and 4) top analytics tools for product managers.