Blin have a 2 meaning. 1. Food - like a cake, round form. 2. Just a word, often meaning a disapointment, may be other not very strong bad emothions.
Examples
1. Блин, зачем ты это сделал? - Ehh/uhh/ohh, why you did it?
2. Блин, сегодня воскресенье! - Damn/Ohh/Why/Wow, today is sunday!
3. Я хочу съесть блин/поесть блинов - I want to eat a cake...