1. An amount of something that you can measure or count. English = quantity, number.
2. Any of the signs such as 'two', 'nine' or 'eleven', or the symbols such as 1, 2, or 47. You use them to say how many things you are referring to or where something comes in a series. English = number.
3. A number a teacher or examiner gives your work to indicate how good or bad your work is. English = mark.