A communications closet has a device that contains 48 ports. The device's sole function is to provide the ports. What type of device is in the closet?

Patch panel.

Explanation:

In this scenario, a communications closet has a device that contains 48 ports. The device's sole function is to provide the ports.

Hence, the type of device that is in the closet is a patch panel.

In Computer Networking, a patch panel can be defined as a passive hardware device in a local area network (LAN) which comprises of ports that are primarily used for the connection and management groups of incoming and outgoing LAN cables for network devices. The main purpose of a patch panel is to neatly connect and organize LAN cables such as RJ-45 cables, fiber-optic cables, cat 5 or 6 cables, telephone lines etc.

Additionally, a patch panel typically helps network engineers or owners to mitigate the problem of cable cluttering, reduced cable costs, easier maintenance of cables.