Most likely, because your workplace_ linked device reported that it was in a new location. A new location is a place that the system has never recorded. If you’re a new user you may receive a couple of these emails. If you travel for work, you’ll receive emails like this more frequently.
Locations will get reported if you haven’t been in an area for more than six months from the date of your last activity. That said, sometimes the location shown is inaccurate.
If you’re concerned about activity on your account, review your account security.