When certain undesirable conditions occur in a jukebox (from hardware failures, to unexpected reboots or even just a full cashbox) the jukebox sends out an alert.  Tempo shows you how many alerts are active on your route the Home page, just below the Live Route section.  

The first box indicates total alerts, and the next three boxes separate the total alerts into eitherSystem (software or hardware issues not temperature-related), Temp (when one or more components in a jukebox reports high temperatures that could lead to a hardware failure) and Money(when a payment means is full or not functioning properly, preventing the jukebox from accepting money).

By clicking the number in each category, you will be presented with the details for that group.  Alerts will be listed by Location, and clicking an alert is a short-cut to the Location > Technical > Alert screen where you can find additional troubleshooting tips.