This application was developed by the Monster Hunter World team, in order to make it easier for players to find the information they need about the monsters they encounter in the game. In Investigations and Monster Field Guide/Researcher, the Elemental Weakness appears next to their name. 

The most important thing about this application is that it saves you the trouble of browsing the wiki or monster guide. It displays the monster's weakness and abilities in the game in an easy to read way, which means that you don't have to go through the trouble of finding the information in the game itself.