6 to the power of six. When you divide a number or variable with an exponent by the same number or variable with an exponent, you subtract the smaller number from the larger number.
A fraction in algebra signifies division so you are taking what is above the line and dividing it by what is below the line.
Since your larger exponent is on top, the answer is 6 to the power of 6. The 6 on the bottom becomes a 1 and in fractions, if the denominator is one, you can remove it and just show the top number.
Now if the problem was reversed, your answer would be 1 over 6 to the sixth power. You would have to keep the 1 on the top.