It sounds like you are familiar with the idea that " is " = " 是 “ but the word " is " can also be used as a "Copula". I'm not an expert, but I think that is what is being used here. The word " is " here is being used to link "thing I have to do" and "get organized". You can also look at it this way: Just like we would say "The WATER is HOT", you can look at "THING I HAVE TO DO is GET ORGANIZED". I hope that helps.