The contention of the bards is like when two kids argue about who is the best at something, like who can run faster or who is the best artist. But instead of kids, it's a bunch of people who are really good at singing and playing instruments called bards. They argue about who is the best at making up songs and telling stories.
It's kind of like a big competition where each bard tries to outdo the others by singing a better song or telling a more interesting story. They might even make fun of each other a little bit to try and prove that they are the best.
In the end, there isn't really a winner since all of the bards are really talented in their own way. It's just a fun way for them to show off their skills and have a good time together.