Absolute value means "distance from zero" on a number line.
One number that has an absolute value of 6 is 6. This is because 6 is 6 units away from 0 on a number line.
On the other hand, -6 would also have an absolute value of 6. This is because -6 is 6 units away from 0.
Think of the absolute value of any number is the positive version of that number.