As well as producing reports from the report builder you can also produce graphs to visually represent the data, which can sometimes make it quicker and easier to digest. However it is also important to note that the graphical reporting functionality in Totara has not been designed to replace any dedicated graphical reporting packages. The reports produced are meant for inclusion in Blocks and Dashboards etc. rather than as a comprehensive reporting tool.
There are advanced settings for graphical reporting that will allow you to customise the look of your graphs. You can find out more on the Advanced settings page of this documentation.
You can see examples of different graph types on the Totara Help documentation.