Mr Teeth

Hi there, this question may be due to the fact it's been a long week... but can someone explain in layman's terms (ie simply, haha) what the "IK Multimedia AmpliTube 5 SE BDL" actually is please...? I've received a download with my purchase of a Behringer interface which is due to arrive soon enough, but I'm trying to understand what the freebie is for before I go ahead and install on my laptop. Cheers! K