-3 > n is the same as n < -3 after you flip both sides and flip the inequality.
To graph this, we place an open hole at -3 on the number line. Then we shade to the left to indicate all values smaller than -3. The open hole says "the endpoint is not included". This is because -3 is not smaller than itself.
We would have a filled in circle if we had "or equal to" as part of the inequality, but we don't.
The graph is shown below.
