I want to learn a new language, but I have no idea what language to learn. I am very busy normally so I don't really want it to be something I have to concentrate my full attention to, but I want it to be fun. Any ideas?
I definitely recommend Swahili then. It's not nearly as challenging as most of the other languages on Duolingo and is incredibly fun and unique! I haven't tried Esperanto but I hear that it is extremely easy I'm just not sure if it's fun though and is not at all widely spoken.
What's fun will really depend on you. Some people might think French is fun but others might think it's agony. You'll have to research cultures that you find fun and interesting, or sounds and appearances of languages while written if that is more important to you. There are languages who just have more to learn than others without being easier or harder than other languages; but if time is important, I don't recommend any languages with very different writing systems like Japanese or any of the Chinese languages. Might be best to stick with the typical common Romance languages Spanish, French, Italian, and Portuguese. Or Germanic languages German, Dutch, Norwegian, Danish, and Swedish. Consider how likely it is you'll use a language, usefulness can be a good motivator. Looking at demographics online of your area or area you want to live in can be good way to find out what languages you could get to most use of. My area that I want to live in my state, Mandarin, Japanese, Korean, Arabic, Hindi, and Spanish are the best ones.
Taking this quiz: https://matadornetwork.com/life/language-best-fits-personality-quiz/ might help you choose a language :)