Goals are essential when you define your analysis objectives. You can use them in different ways, either to analyze the population having achieved the created goal or to analyze the way screens and zones contribute to achieving a chosen goal.
Using Goals in Segments
You can create new segments based on goal completion, using a goal - read more here.
Using Goals in the Analysis Context
You can define your analysis parameters inside the Analysis using a goal - it lets you create a segment on the fly based on users who have (or haven't) completed a certain behavior.
Using Goals as Conversion Goals
You can select a goal as a Conversion goal, to get an overview of if users have completed the goal (based on the settings in your Analysis Context).
You can select a Conversion goal using the goal selector inside the Screen Metrics, Zoning Analysis ("Conversion rate per tap"), Dashboards and Alerts.
E.g. in the Zoning: select a goal in Conversion goal selector ("Conversion rate per tap/swipe")