When you want more of something, you don't have enough. This is a comparative word that has to do with addition. It's also the opposite of "less."
When you like something, it's hard not to want more of it. Most people want more money and friends. If you favorite TV show was canceled, you wish there were more episodes. If you're full and someone offers more cake, you could say "No! I can't take any more!" When you see the word more, something is getting greater in size, number, or quality. People who are greedy are constantly screaming "More!"