In synthetic monitoring, you may simulate your application from various browsers and geographic locations to optimize its performance. For instance, let's say you simulate 10 stages of your application from 7 different locations at a 5-minute poll interval. If you're using both synthetic and real user monitoring, you would end up consuming 20k (10x7x12x24) page views per day from your RUM license.
In such cases, you can exclude specific user agents. A user agent is a specific piece of software that communicates between the server and the user browser. By excluding specific user agents, you can avoid page views from being unnecessarily consumed by RUM.