Frequency Capping lets administrators manage the number of communication sent to a contact through different channels on a daily, weekly, or monthly basis. This defines how many times it's appropriate to contact a contact within a certain period of time based on the time interval between two communications and the number of communications received in a day or week or month.
It's essential to maintain the appropriate number so that you don't spam your contacts or mail them rarely. It is also preferred to have a defined interval period between communications so that it does appear annoying to the receivers, which can also be customized in the same section. The ideal limit of emails expected per month for a contact is two.
Click Settings icon on the top-right corner of the screen.
Click Frequency Capping under Tracking and Sending Limits.
In the table listed below, you will find selection for Email, SMS and Whatsapp and the functionality works the same for all the three types.
For every communication type, you can fill in the following information:
Daily Limit - The maximum number of emails a contact should receive in a day.
Weekly limit - The maximum number of emails a contact should receive in a week.
Monthly limit - The maximum number of emails a contact should receive in a month.
Message Interval - The time interval between two consequent emails. You can choose to select either days or hours between consecutive emails.
Click Save.

When the check box is enabled, all workflows abide by its limit and your workflows will not be able to send emails/SMS/Whatsapp messages if it touches the limit. Once an activity is denied by the Cap, it does not get queued and straightaway fails. You can find such failed cases from the ignored section in the workflows.
You can disable the setting globally if you do not want to disable it individually for all the workflows. You can also disable Frequency capping for certain workflows if you want to send more communication than the set limit even if the frequency capping is enabled globally.