This is an internal expansion card for a computer, specifically a dial-up modem, designed to be installed into an available slot on a computer's motherboard (likely PCI based on the connector type).

Key Features and Components:
Ports: The metal bracket features two small, side-by-side ports labeled "LINE" and "PHONE". These are RJ-11 jacks for connecting to a standard telephone line.

The "LINE" port connects directly to the wall telephone jack to establish a dial-up internet or fax connection.

The "PHONE" port is a pass-through that allows a standard analog telephone to be connected so the same phone line can be used for both voice calls and data, though not simultaneously.

Circuit Board: The main green circuit board contains the electronic components necessary for modulation and demodulation (modem functionality).

The chips, capacitors (the blue components), and resistors work together to convert the computer's digital data into analog signals for transmission over the phone line and vice-versa.

One of the visible chips has the branding "Dax", which could be the manufacturer or a component brand.

Connector: The golden-fingered edge connector at the bottom is designed to plug into an expansion slot on a computer's motherboard, likely an older PCI slot, allowing the computer to communicate with the device.

Function:
The card's primary function is to enable a computer to connect to the internet or send and receive faxes over a standard analog telephone line using the dial-up method. These connections are typically very slow by modern standards, often maxing out at speeds of 56 Kbps.