What does this red line mean? How do I change it or explore why it was imported this way?

[Stacy Banks]

[Tony Rossiter]

@Stacy Banks 

Those are the Card Colors that the board is configured with.  Looks like you're possibly using Priority as your color scheme?  

Here's how to change/remove them: 

https://confluence.atlassian.com/jirasoftwarecloud/customizing-cards-764478020.html#Customizingcards-coloursConfiguringcardcolors