From the Trends section of the website, you can see all the different metrics and how they line up. The time window can also be adjusted, from the last few months (default) to an entire year at a time.
Raw data for most metrics is very hard to interpret. The data is processed & simplified to show the actual trend and extract signal from the noise. This is done through filtering out bad data, highlighting outliers, generating averages over various time periods, and many other techniques.
From the Goals section of the site, you can set your targets. This applies especially for complex topics like nutrition, where you can set your daily calorie range or protein targets.
It can also be used for customizing your targets for daily activities like steps or sleep!
Most metrics will show more details. From the detail page, you can compare it to other metrics to search for correlations, or hover and click on the graph to learn more about a specific day.