This condition checks a field's value to determine how a contact should proceed in the automation. 

When would you use this?

Let's say for example you are looking to send a set of emails to Leads for nurturing into Customers and you want to make sure when they turn into a customer they don't continue to get the Lead Nurturing messages. 

You would want to first have a custom field created for lets say Status. In that Status field you would want to show the status of Lead or Customer. 

Then you would use the Check Field Condition and set the settings based on the Field to check, and the Equal status and then what it should be looking for or the "Field Value".

In this scenario I chose the Field "Status" to "Equal" and the Field Value to "Customer"

With those settings now I can check to see if the Field says Customer and select an Action to proceed this check.