Security emails show the approximate location of a sign-in based on IP geolocation. VPNs, mobile networks, and internet providers can make the city or region look different from where you actually are, so an unfamiliar location does not necessarily mean someone else accessed your account.
If the sign-in was you, no action is needed.
If you do not recognize it, reset your password and review your account security settings.
Verification codes must be entered on the Venice website, not by replying to the email.