With Rarity owning multiple venues, she has a lot to deal with on a daily basis. She has needed an abundance of help from her friends over the past few years, and every time she needs some assistance, Applejack goes out of her way to help.
Now that Rarity has some vacation time, she feels that it's only right that she helps Applejack in return. However, she's not really one for farm-work. Now it's up to Applejack to show Rarity that work can be fun.