You know solution concentration as w/w percentage - so you know there is 52.5g per 1000g of solution - but what you DON'T know is what volume this solution occupy - and by definition of molar concentration you MUST know the volume. That's where the density comes into play.
ChemBuddy lecture puts emphasis on the universal approach to this type of problems, so that you will know how to convert between any concentration types, but it also gives you - at the very bottom of the page - simple formula that you can use in this particular case.
However, you are given enough information in your question so that you can find molarity just with simple reasoning. 1L of solution is 1080 g, 5.25% of that is NaClO. Calculate NaClO mass, convert that to moles and that's your answer (you have to divide it by 1L which won't change the number, just units)