Alright so lets start with prime numbers.
A prime number is a number that can only be divided evenly by 1 and itself. For example, 7 is a prime number it can only be divided by itself and 1, if it's divided by anything other than 1 and itself, the answer will be a decimal number. 4 is not a prime, because it can be divided by 2.
Now onto negative numbers.
Normal numbers exist on a line, starting with 0, all numbers to the left of it are positive, like 1, 2, 3, 4,... , but to the right of zero are the negative numbers ...-4, -3, -2, -1. Negative numbers are the opposite of positive numbers, so that means the larger the number looks, the smaller the quantity is, so -20 is actually smaller than -10. Think of it like this, would you rather owe someone 20 dollars or 10 dollars? A number line with positive and negative numbers would look like
.....-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5,........
Notice how the negative numbers count down from left to right, this is because the greater numbers on the number line are to the right and as I said before, the smaller a negative looks, the greater it actually is.
I hope all that helped.