Alerts tell you when events occur that you may want to take action on.
An alert is indicated by an orange starburst on the top right corner of the item. The number shows how many alerts there are for that specific stock.
To view the alerts, simply click once on the item, then choose the Show Alerts option.
The alert will display as a pop-up with any key information.
You can manage the companies and funds you receive alerts for under the Settings tab on the top of your Playground: