The dashboard graphs show both the blue dots which represent each rounds performance and a blue trend line which indicates how your performance is changing over time.
This rolling average, or trend line, is the average of the last 7 rounds that you have played.
Rolling averages are important as a representation of how you're performing over time. A focus on each individual round can be misleading as golf improvement is not linear, and there will always be good rounds and bad rounds in your improvement journey. Ultimately you're looking for the improvement trends to be moving up, which shows an overall improvement in your game.