Metrics show quantitative information about visitor activity, such as Views, Click-Throughs, Reloads, Average Time spent, Units, Orders, and Revenue. Along with dimensions, they are the foundation of reports and help you view and understand data relationships. They let you perform side-by-side comparisons of different data sets about your website.
Metrics and associated data are displayed in the columns of reports. Broad categories of metrics include:
Traffic metrics: These show data about the volume of visitors.
Conversion metrics: These show data about success events, such as purchases, downloads, or any other action that you want users to take on your website.
Calculated metrics: These are metrics you create by combining metrics.
Video metrics: Marketing reports provide support for tracking a number of video metrics, including total views, time spent, and completion rates.
Social metrics: These help you measure your brand's presence on the social web. Social metrics work with Analytics standard metrics. By combining these with calculated metrics, you can view a report that shows how often a product is mentioned, gauge product sentiment, and see how Social metrics correlate with Analytics key performance indicators.
For more information on how you can hide metrics in some user interfaces, go here.