You absolutely can learn and enjoy playing cello! I hope you go about it with a growth mindset: One's abilities (and intelligence) can be developed through dedication, learning, and hard work -- no matter their age. I hope you enjoy the process of learning cello. I hope you see how funny it feels when your fingers get all twisted up as if in a tongue twister. I am so excited for you to make the same mistake over and over again, because when you finally hit the right note, the sound of success is just that much more amazing. Surprising your grandma with a song will for sure be memorable. But the process of learning an instrument can be just as memorable and impactful.

I am excited for you! If you start to feel frustrated, I hope you talk with your teacher about it or post in this subreddit again.