Let's dive into this subtraction. We'll start with 23215 and subtract 12397 from it.

Step 1: We'll start by subtracting the digit 7 and the borrow 0 from 5 in column 1 and get -2.
We add -2 to 10 and get 8 as the first digit of the result.

Step 2: We'll start by subtracting the digit 9 and the borrow 1 from 1 in column 2 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

Step 3: We'll start by subtracting the digit 3 and the borrow 1 from 2 in column 3 and get -2.
We add -2 to 10 and get 8 as the next digit of the result.

Step 4: We'll start by subtracting the digit 2 and the borrow 1 from 3 in column 4 and get 0.
0 is the next digit of our result.

Step 5: We'll start by subtracting the digit 1 and the borrow 0 from 2 in column 5 and get 1.
1 is the next digit of our result.

So, 23215 - 12397 = 10818.