can't understand object recognition

Ofer,

As far as I know, msiexec is a Windows Installation process. When you launch an installation program, there can be several msiexec processes in the system. One of them contains windows for interacting with the user while the others don't have windows and perform some helper actions, for example.

You are right about the index. In your case, 2 is the index of the msiexec process. TestComplete uses it to distinguish this process from other msiexec processes.