This device is a 3.5mm audio jack splitter / converter (often called a headphone & microphone adapter).
What it does
It converts one 3.5mm headset jack into two separate ports:
One port for headphones/speaker (audio out)
One port for microphone (audio in)
Why it’s used
Many phones, laptops, or PCs:
Have one combo jack for both mic + headset
But some headsets have separate plugs for mic and headphone
This adapter lets you:
Use a headset with mic on a PC or phone that has only one jack
Or connect external microphone + earphone at the same time
Common uses
Online calls / Zoom / WhatsApp calls
Gaming headsets
Recording voice
Laptop or phone audio setups
How to use
Plug the small male jack into your phone or laptop
Plug your headphone into the symbol port
Plug your microphone into the symbol port