Answer Description

A privacy screen (or privacy filter) is a device applied to a computer monitor to make it difficult to see the screen unless directly in front of the monitor. This provides limited protection against shoulder surfing.

Wikipedia

In computer security, shoulder surfing is a type of social engineering technique used to obtain information such as personal identification numbers (PINs), passwords and other confidential data by looking over the victim's shoulder. Unauthorized users watch the keystrokes inputted on a device or listen to sensitive information being spoken, which is also known as eavesdropping.