BL manhwa refers to Boys' Love comics or graphic novels that come from South Korea and feature romantic or intimate relationships between male characters.
Well, 'sugar and spice fanfiction' could be about a variety of things. It might be related to stories that are sweet and full of charm, perhaps with characters that have a sugary - nice personality combined with some spiciness, like a bit of sass or an exciting edge. It could also be set in a world where there are elements symbolized by sugar and spice, like a magical place where sweet treats and spicy potions play a role in the plot.
I'm not entirely sure specifically what 'Sugar Spice Visual Novel' is about. However, visual novels usually have a strong narrative. It could be about a group of friends, where some are really sweet and kind (like sugar) and others are more feisty or have an edge to them (like spice). There could be a plot that weaves their stories together, with different choices the player can make that lead to different outcomes.
Well, a rut bl manhwa usually features male-male romantic relationships and explores various themes related to love and emotions. It's a popular genre in the world of manga.