The word * Maths * is short for the word * Mathematics *. When you start school you learn how to add, subtract and multiply.
1+1 = 2
2+1 = 3
2 x 2 = 4
You keep doing harder and harder sums and when you go to secondary/high school you study Algebra and Geometry.
Algebra looks like this;
2a + 2b = 6
5b + 6C + 3d = 44
Geometry involves Lines, Squares, Angles, Triangles, etc
You learn all about these when you study Geometry in Secondary/High School.
When you go do University to study Engineering you learn harder Maths like the following;
Engineers use Maths like this when they are designing, Rockets, Spacecraft, Satellites, Computers, Skyscrapers, Video Games, Hospital Equipment, Cars, Televisions, and so on.
So, you can see that it is very important to practice your Maths in school if you want to become an Engineer!