Languages.txt is a user created slot type. Call it Languages when adding it to slots Intents.json is the intents object that you create create. Utterances.txt are the utterances in order to ask the alexa skill.
To trigger the lambda function, say "Alexa, ask roaster (or whatever you make the invocation name) to roast John". You can also ask the skill to roast people in different languages. The current supported languages are: Russian, English, Hungarian, Portugese, Spanish, German