You can add handles column into the task manager by right-clicking on the headers bar and selecting "Select columns"
By default threshold for these monitors is 10000 handles, and 2GB private bytes.
For handles values above 10000 is not something unexpected, Microsoft recommends to increase threshold for handles to 30K for SCOM agents with management packs which produce big number of monitored objects.
More than 2GB of private bytes is also a high, but not unexpectedly high value. When there are a lot of monitored objects this threshold could be easily breached. Check if this Collector system is alowed to consume more memory and increase private bytes threshold to 3GB. By the way, the health service or monitoring host processes should peak at these values, but not always stay at that level.
Check if you have any other errors or alerts for this server. Check Operations Manager event log on the Collector Server, if everything is working smoothly, you can just increase the threshold if you are OK with such memory usage on this Collector Server. If you notice any other errors about failed workflows or dropped data - it's an indication that SCOM agent reached it's performance capacity and cannot scale anymore. In this case solution would be to add another collector into your monitoring infrastructure, this should significantly off-load your current Collector system.
Let me know if you have any other questions.