Anyone to help me understand the meaning of "*m" in c language.

Question

The * symbol meaning on the variable.

Answer 1

m is normal variable while *m is pointer variable. Pointer variable is a variable that can address of another variable..
Ex:
int a=10,*p;
p=&a;
Then p contains a address, *p return a value 10.
Read about pointers in C.
https://www.sololearn.com/learn/C/2933/

Answer 2

first you need to understand pointers.
lets say you declare a variable a:
int a=1
then 1 is the actual value.
&a lets you access its adress

if you declare a variable like this
int *b;
it is a pointer.
you can store the adress of a in b like this:
b=&a;

to acess the value that is stored in memory on which b points you can use *b

roughly.
Understanding pointers is essential.
I suggest to look it up in detail.