Gastric Cancer must be the most confusing cancer there is?

I am so confused about this. Google does not help, nor do my parents!

So, recently, my mum thinks that I am old enough to know that my Grandpa has Gastric Cancer. I am finding it as a very tough topic to understand.

I will tell you what I think is right.
-Gastric Cancer is Stomach Cancer,
-There are two types, Benign and Malignant tumors
-Benign is the one that can be removed and wont grow back.
-Malignant is the one where it will grow back and if fatal.

Have I understood this right? Please correct me if I am wrong.
Also, where can I read about the cure? If there is one?
Thank you!