Think of a number line with zero in the middle. Everything on the right is bigger than zero and everything on the left is smaller than zero. That means you can pick any number on the right, so that’s called a positive number, and it will satisfy x>0 where x is the number. So examples would be 7 and 59. Any number on the left is negative and is represented by x<0. So examples would be -1 and -79.
8<m means that 8 is to the left of m, which is another way of saying m is to the right of 8. Note that the pointy side of the inequality sign points to the smaller quantity. If we write m>8 the pointy side is still pointing to the smaller quantity. If quantities swap sides then the inequality turns round to point to the smaller quantity.
15>r means r<15, so r can be any number less than 15. For example: 0, -15, 3.5, ¾, -83. All these numbers are to the left of 15 on a number line.