The LGE Mobile Composite USB Device is a driver used for communication between your LG mobile device (such as a smartphone or tablet) and a Windows PC. This driver allows the device to function correctly when connected via USB, enabling a variety of functions like file transfer, synchronization, debugging, or using your phone as a modem. The "Composite" part of the name usually indicates that the driver supports multiple functions simultaneously, such as MTP (Media Transfer Protocol), PTP (Picture Transfer Protocol), or USB tethering.
When you connect your LG device to a Windows computer, this driver allows the operating system to properly recognize the mobile device, allowing you to transfer files, access internal storage, and use features like USB tethering or smartphone management tools.