Hi there, I'm in year 10 and I take comp sci, econ, music and french (+ core subjects). Comp sci isn't that difficult in my experience and if you enjoy it, it would be good to take. I think taking comp sci and business together would be really useful, considering that in the future many companies will use technology and it would be good to have some knowledge in it. I would recommend doing comp sci and business
It's really up to you though, spanish is also a good option and many people in my school take it. Just keep in mind that languages have a lot of workload so taking both Cantonese and spanish might take up some of your time. It's manageable though, so if you really love Spanish then go for it!
Whatever you do, I'm sure you'll enjoy it. Good luck choosing your options!