Positive economics is concerned with facts and is value-free. It is a scientific approach to the discipline, where economists explain the outcome of a particular policy, but are not expected to take sides. Positive statements can be tested true or false.
Normative economics is concerned with value-judgements, and is a non-scientific approach to the discipline. A normative statement is an expression that something is right or wrong, so often includes the words ought, should, fair, unfair, better or worse.