You may want to first read up on what is a process and what is a thread and thread pools in WebSphere.

The Tivoli Performance Monitor can be used to view the number of threads being used in a pool.

1. In the WebSphere admin console, select Monitoring and Tuning > Performance Viewer > Current activity.
2. Select an application server.
3. Expand Summary Reports > Thread Pool.

In this example, the graph shows a spike when threads in the WebContainer thread pool are in use.