Which device is primarily used for visual output from a computer?

The monitor is specifically designed as the primary device for visual output from a computer. It displays images, text, and videos generated by the computer's graphics card, allowing users to interact with the computer's interface effectively. The monitor provides real-time visual feedback from applications, enabling users to view their work and interact with graphical user interfaces.

While other devices listed may also have visual output capabilities, they serve different primary functions. For instance, a printer produces a physical copy of documents and images but does not provide immediate visual feedback from the computer. A speaker outputs audio rather than visual content, and a keyboard is an input device that allows users to enter data into the computer. Thus, the monitor stands out as the primary means of visual output, fulfilling the essential role of displaying information in a user-friendly manner.