what is jamun - #25255

I am really curious about this fruit called jamun. A few weeks ago, my grandma was talking about it and saying how good it is for health. I never heard of it before! She mentioned something about jamun being good for diabetes or something like that, which caught my attention 'cause my dad struggles with that. I tried to find some in the local stores but only ended up confused. What is jamun exactly? Is it a berry? I think she said it has a sweet and sour taste, which sounds interesting. My friends said it’s hard to find in some places but they have seen these purple fruits in the market sometimes. I've read that jamun can help with digestion too, but I wonder if it has any side effects. Like do you need to eat a certain amount for it to be effective, or can you just snack on it? Really hoping to learn more 'cause I want to help my family with some natural remedies!