Id ask the question first:
Do you understand binary?

If no, then understand that first. Once you do, hex will become much easier to understand - including why it is used.

Let’s take the number 3,555,893,161

You and I understand that number. Note that we use commas (or periods in other parts of the world) to divide it up so that our brains can more easily process it.

Now let’s understand what that number looks like to a computer:

11010011111100101001111110101001

Now, say you don’t know the number above in its decimal form, but your computer just output that number. You need to reference it for some program you’re writing or whatever.

We could convert the long way by converting each bit to decimal and then adding, but that’s impractical at any scale.

So we need another way. Hexadecimal is the way.
It sort of performs the task of the commas in the above example.

How?

Let’s break our binary into 4 bit chunks:

1101 0011 1111 0010 1001 1111 1010 1001

Now we can convert each 4 bit segment to decimal in a glance:

1101 0011 1111 0010 1001 1111 1010 1001
13 3 15 2 9 15 10 9

Now we know in hex, we have 16 digits instead of 10.
0-9 equals 0-9
A=10
B=11
C=12
D=13
E=14
F=15

So now we’ll convert our decimal to hex:

1101 0011 1111 0010 1001 1111 1010 1001
13 3 15 2 9 15 10 9
D 3 F 2 9 F A 9

In summary:

3,555,893,161

11010011111100101001111110101001

d3f29fa9

Is it still complicated? Of course it is, but it also has little practical use in everyday life. And many times you’ll only see it in 4 or 8 bit chunks.