Libidn2 is an implementation of the IDNA2008 + TR46 specifications (RFC 5890, RFC 5891, RFC 5892, RFC 5893, TR 46)
Before using the library, you have to load it:
module load profile/advancedmodule load libidn2
You can find documentation on the module, with the command
module load profile/advancedmodule help libidn2