|Your question doesn't make sense. |
You have a number of emails sent, in column A, and a time, in column B, but nothing that tells you how much time elapsed. You would need a third piece of information - another time - to establish a time frame to measure over. Without knowing the amount of time you're measuring, you can't calculate "anything" per hour, because you don't know how many hours you are calculating for.
column 1: 50 emails
column 2: 12:30pm
you'd need a third column, showing another time, to calculate emails per hour. Let's say you have a third column, and it says "1:30pm". That would tell you that an hour had elapsed since 12:30. Then, knowing that 50 emails were sent, you would know that the answer is "50 emails per hour". The formula for that is simple, and I or someone else can show you how to craft it.
How to ask a question.