A lot of university have requirements like ;GCSE Minimum 6B in GCSE MathematicsWhat does it mean Is it taking at least 6 subjects with B Can I take one mathematics subject only

The requirement "GCSE Minimum 6/B in GCSE Mathematics" means that you need to have achieved a minimum grade of B in your GCSE Mathematics exam. It does not refer to taking six subjects with a grade of B.

You can take only one mathematics subject and still meet this requirement as long as you achieve a grade of B or higher in that subject.