If there are new notifications, you will see this from the notification count at the workbox icon. Clicking on the icon or pressing g and then n you opens the workbox to view you notifications. LINCHPIN aggregates likes and comments (see screenshot below) so you are not swamped by notifications.
You can then jump to the page or content in question, like/unlike it, reply to it, or stop watching it if you no longer want to receive notifications about it. You can also receive notifications via email from LINCHPIN, most commonly this is enabled by default via the autowatch feature.
You can even recieve your notifications on your smartphone or other mobile device too. See Using Confluence on a Mobile Device for more.