I can understand maths as it applies to my everyday life. I can use statistics, averages and percentages, I can weigh and measure accurately for cooking, I can work out money and I know whether or not my change in a shop is right. I can use and understand basic formulae needed to create and use Excel spreadsheets. I work with them regularly and have no difficulty. That is basic numeracy I suppose.
Move onto things like algebra, pythagoras theorem, pi, and many other theorems etc. and I am lost. I look at a page with them on and I literally just cannot read it or make sense of it at all. I don't need or use them in my everyday life either. If I had needed to get a B at "O"Level, as it then was, I would still have been at school trying for it now, at the age of 48.
I think someone earlier in the thread suggested that everyone if taught correctly should be able to master all aspects of subjects like maths. I would disagree. It is a very wide subject indeed. We are not all equal in all subjects. I really struggled with maths at school, but now that I have uses for some of it in my daily life, and with more maturity too, I have come to terms with much more of it.
Maths was my achilles heel, but I was good at languages. I would not try to suggest that everyone can master foreign languages given the right teaching because it just isn't that simple. Same with maths. Why should it be any different?