The first-year mathematics units are based around four large topic areas:
Logic and Proof is, among other things, the mathematics of how computers work - both at the hardware level, where the start of Maths A deliberately overlaps with COMS10015 Computer Architecture to some extent, and at the software level because the modes of thinking here can be used to prove that a program does what it should - or to design a program in the first place.
Combinatorics and Probability is the first step towards the science part of Computer Science - one of the aims of science is to build models that describe parts of the world, even when we do not have complete and accurate knowledge. The material you learn here is also a foundation for machine learning, an area that combines aspects of computing, mathematics and science. When an algorithm “learns” something, there is usually a probability distribution being modelled in the background.
Linear algebra is about vectors, which among other things can be used to describe objects in 2D, 3D or even much higher-dimensional spaces. There are obvious applications to computer graphics and image processing, but linear algebra in one form or another crops up all over Computer Science, whether you expect it or not.
Analysis and Statistics continues the theme of scientific modelling. One particular application is high-performance computing which is used among other things to run simulations of everything from weather and climate models to aerodynamics to social systems to the spread of infectious diseases. The statistics part will help you to produce scientifically valid results: if for one of your projects you take some code and make it run faster, you can now properly evaluate your achievement and compare it to other work in related areas.