This rule allows you to set the maximum number of orders from the same IP address in a given time frame (hours). Any additional order in the same time frame will be considered risky and will make the rule check fail.
In the image below we set the number of orders to be a maximum of 2 in one hour. So, starting from 3 orders in one hour, this rule check will fail.
To enable this rule, go to General settings > Rules settings and Enable check for attempt count.
For more details about the rule weight settings, please, read this page of the documentation.