Here's what this description means:

4x4 Matrix: This refers to the layout of the keypad, which consists of 4 rows and 4 columns, resulting in a total of 16 keys. Each key is positioned at the intersection of a row and a column, forming a grid.

Keyboard Keypad Module: This module is designed to work as a keyboard input device. It allows users to press keys to send electrical signals or data to a connected microcontroller, computer, or other digital devices.

4x4 Plastic Keys: The keys on this keypad module are typically made of plastic. Plastic keys are commonly used in these modules due to their durability and cost-effectiveness. Each key can be pressed like a button to register an input.

Switch: Each key is equipped with a switch mechanism. When a key is pressed, the switch makes electrical contact, allowing the module to detect the keypress and send corresponding signals.