My grandfather was holding a grudge against me

When I was 10 years old, I lived with my grandparents in their house. That house was located in a town near to Bogota, the capital of Colombia. My school was in Bogota so my parents pay me a school bus for take me and my brother to home. Every day, when we arrived to the house, that actually was a farm, my grandfather went to the main entrance and received us. As you can imagine, in the school bus we were a lot of children, so we used to play while we went to our houses. 

One day, I was in the school bus and I listened some friend that say a bad word, but in that moment, I didn't know that was an offensive word... So, as soon as I arrived to my house, I said to my grandfather "Hola boludo" in Spanish, that's mean something like "Hi stupid"... He looked at me and seemed very upset and in that moment I understand that I said some bad word and immediately I felt that he was holding a grudge against me... We went to the main house and there was my grandmother, she noted that something happened... That night, we had an special dinner in the house because was my cousin's birthday, but my grandfather didn't want to enjoyed the party with us because I... I felt really bad and sad, I messed up the celebration... Then, my mother told me "you said some bad word to her grandparent and he is holding a grudge against you, you should go to him and ask him for forgiveness". So I went to my grandfather's room and I sat down in his bed and I gave him his favourite dessert and I tried to made up for my mistake. I said him that I was so sorry about the word that I used and will never happened again. At that moment, I think, he understand that my intention wasn't to offend him, I was only a kid...

Since that day, I learned that everything that I heard, I should ask to someone adult for ask the real meaning, in order to not repeat this unfourtanelly accident. Then, now I can know how words are "bad words" or maybe are inapropiate for say to anybody. I feel soo lucky that my grandfather has taught me that lection... I love you grandpa :)