can i have more than two devices associated with my pc?
I have a new iPhone se. I already have two iPods associated with my iTunes account. Will I have to remove one of the iPods in order to back up to my pc?
Yes, it is possible.
See also -> Check your Apple ID device list to see where you're signed in
Check your Apple ID device list to find where you're signed in - Apple Support
- add also your new iPhone se to your account.
For back up, see this Apple article: How to back up your iPhone, iPad, and iPod touch
How to back up your iPhone, iPad, and iPod touch - Apple Support