I'm not entirely sure as I haven't read it specifically. But generally, a 'villainess' light novel might be about a female character who is initially seen as a villain in a story, perhaps in a fantasy or fictional setting.
The protagonist who is reincarnated as the villainess is very important. Also, the prince is a significant character as he is one of the main love interests in the story. Then there's the heroine of the original game who also plays a role in how the story unfolds.
In 'My Next Life as a Villianess Light Novel', the key plot point is the reincarnation of the lead character into the role of the villainess. She uses her knowledge of the game to rewrite her fate. She befriends characters that were supposed to be her enemies in the original game plot. Her attempts to change the story lead to various comical and heartwarming situations. She also tries to find her own path in this new world, rather than following the doomed path of the villainess.
Yes, Kill la Kill originated as a manga. It gained popularity and was later adapted into different mediums, with the anime being particularly well-known.
To Kill a Mockingbird was an English novel written by Harper Lee in 1960. The novel was translated into many languages and widely read and discussed around the world.