Apps built into Windows 10, like Mail, Windows Clock, and Weather, display tiny numbers or markings, called badges, on the taskbar icons to direct you to the right app: Mail uses them to tell you the number of new emails, Windows Clock the active alarm, and Weather the current weather changes. If you’re not happy, you can disable this form of notification.
Use the Windows+I shortcut key to open the Windows Dashboard. After a click on the Personalisation category, select the Tray entry in the left-hand column. Scroll down in the main window and set the Show badges on tray buttons switch to Off to stop badges from appearing in the tray.
Note: if the Use Small Tray Buttons option in the same window is turned on, the Display Badge option will automatically be turned off.