There are two types of ways to control how data syncs from one system to another:
The main application used by customers to control what records sync from one system to another is Workflows. Learn more about setting up Workflow rules here.
Filters in Mappings, on the other hand, are like Workflows however they only restrict when a given field can sync when a record is getting pushed up to another system.
So lets say there are 10 fields in a given update for a particular record and this record passes one of the Workflows the customer has setup, which means it is allowed to sync over to the other system. This customer also wants one particular field to only sync in certain cases so they leverage the Filter feature in their mapping to make it so that only this field gets updated when the rule is met that they have set for the given filter. So in this example, if 1 of the 10 fields happens to be this field that has a filter and it doesn't meet the filter rule, then this field will be left behind but the other 9 will be updated in the given system.
Still have questions about when to use Filters or Workflows? Let us know by clicking on the Contact tab in the top navigation and shoot us your questions.