What is the Viera wireless adapter used for?

There is no wireless adapter by the Viera brand name. However, Panasonic and NETGEAR produce wireless adapters that work with Panasonic Viera televisions. Panasonic TY-WL20U and NETGEAR N300 are two examples. When plugged to a Viera TV, they enable the television to access online content through a wireless LAN router.

With speeds of up to 5.85 gigahertz, the TY-WL20U is a wireless adapter that provides dual band wireless coverage. Able to transfer up to 300 megabits of data every second, the N300 supports the IEEE 802.11n Wi-Fi standard. It establishes a secure connection by using WPA-PSK, WPA2-PSK and 128-bit encryption.