If you think that an idea or a statement is foolish or wrong, you can say that it is rubbish. He's talking rubbish These reports are total and utter rubbish. = nonsense
Rubbish consists of unwanted things or waste material such as used paper, empty tins and bottles, and waste food. unwanted household rubbish = refuse
If you think that someone is not very good at something, you can say that they are rubbish at it. He was rubbish at his job I tried playing golf, but I was rubbish. great