This is called a Message Waiting Indicator (MWI) light and it lets you know you have an unopened voicemail message. When you listen to your voicemail messages from your desk phone, you may notice that there is no option to delete a message - you can only press 7 to archive a message. In this case, archive is nearly the same as delete and once you have archived all messages, the MWI should go out.
Occationally, after you have listened to all messages, the MWI is still illuminated. If this happens, you probably need to open the Dialpad app to clear them. This can be done from a web browser or by installing the app for desktops, smartphones, or tablets - or by searching for Dialpad in your device's App Store.
If you have trouble clearing the unread messages, you can also call Dialpad support at 844-636-4244 (they are available 24x7 and typically you will wait less than two minutes before you speak with an operator).
