Some possible jobs? Lecturer, tutor, statistician, etc.
The maths in it? It depends on what maths you want. If you like applied maths, you learn how to model real world scenarios mathematically. If you like stats, you do stats. If you do pure maths, you do things like vector spaces and topology. If you do financial maths, then you do financial maths (though that's a Commerce major thing).
And how many subjects? Well, I follow a plan. It's a five year course with eight subjects per year.