WlanHelper is used to set/get the operation mode (like monitor mode) for a wireless adapter on Windows.
A little tip
WlanHelper tries to follow the grammar of iwconfig, a wireless management tool for Linux. So if you rename WlanHelper.exe to iwconfig.exe, your command lines for configuring operation mode on Windows will be exactly the same with the alternative on Linux.
Managed Mode (for Linux) = Extensible Station Mode (aka ExtSTA, for Windows)