Final answer:
A Primary Failure on the ECAM is indicated by an automatic display of the affected system page, with a red box highlighting the failure at the top of the screen and an accompanying aural alarm, signifying immediate action is required.
Step-by-step explanation:
An Electronic Centralized Aircraft Monitor (ECAM) is used to display primary aircraft system data and alert pilots to malfunctions. In the event of a Primary Failure, the ECAM will indicate this by displaying the affected system page automatically with the failure indicated at the top of the screen in a red box referred to as a 'Level 3' failure message. This red warning is accompanied by an aural warning. The primary failure message is considered the most urgent and requires immediate action. Additionally, other associated procedures or actions will be listed below the failure message to assist the pilot in resolving the issue.