Any easy way to think of nested for loops is to ignore the fact that they are nested. By convention, you will typically use i for the outer loop's increment counter and j for the inner loop's, which is the most important thing to keep straight in the beginning. If that is a point of confusion for you, it would likely benefit you to use more descriptive names for your increment variables than the letters 'i' and 'j', for example outer and inner.

At any given time when you are trying to structure your program's logic you only need to focus on the for loop that you are working most directly inside - at least when you are starting out and learning about them for the first time.

Your logic is slightly off. I have made some amendments and tested the below which should get your desired outcome:

Copypublic static void main (String[] args) {
    Scanner scnr = new Scanner(System.in);
    int numRows;
    int numColumns;
    int currentRow;
    int currentRowInteger;
    int currentColumn;
    char currentColumnLetter;

    numRows = scnr.nextInt();
    numColumns = scnr.nextInt();

    /* Your code goes here */
    for(currentRow = 1; currentRow <= numRows; ++currentRow){
        for(currentColumn = 0; currentColumn < numColumns; ++currentColumn){
            currentColumnLetter = (char)('A' + currentColumn);
            System.out.print(currentRow + "" + currentColumnLetter + " ");
        }
        System.out.println();
    }

}

Notice how I define the currentColumnLetter within the 2nd for loop, rather than outside of it. I have also replaced the currentColumn referenced in the print statement with currentRow instead

for (int i = 1; i <= 5; i++) {   // outer loop iterates 5 times.
    for (int j = 1; j <= 10; j++) {  // for each iteration of outer loop, 
                                     // inner loop iterates 10 times
        System.out.print((i * j) + " ");
    }
    System.out.println();
}

First iteration of outer loop (10 iterations of inner loop)

i = 1, j = 1
i = 1, j = 2
...
i = 1, j = 10

Second iteration of outer loop (10 iterations of inner loop)

i = 2, j = 1
i = 2, j = 2
...
i = 2, j = 10

...

Last iteration of outer loop (10 iterations of inner loop)

i = 5, j = 1
i = 5, j = 2
...
i = 5, j = 10

As suggested by @user16320675, I combined everything into a single for-loop and it is now working as expected! I didn't even know you could combine for-loop statements with the && operator. User's suggestion that answered my problem was:

for (c1=startC, f2=startF; c1<=finishC && f2<=finishF; c1+=stepC, f2+=stepF)

I just made a couple tiny changes and off it went! Thank you everyone for your help and time!