Summary

The explanation for Threshold Type and Threshold Number can be found at Create object type mapping by clicking on "View fields for object type mapping".

The explanation is as follows

Threshold Type
When objects are missing in the data source, you can specify a threshold for the Update and Delete configurations. This means that Insight will wait with performing these actions until the conditions specified in the threshold are met (days, synchronizations)

Threshold Number
The number of days/synchronizations before performing the actions described above.

Suggestion

An example of how to use these fields would be great. For example

When you have the 'Threshold Type' set to Synchronizations and 'Threshold Number' set to 1, this means missing objects will only be removed starting from the second synchronization. Similarly, if you set the 'Threshold Number' set to 2, the missing objects will be removed on the third synchronization onwards.

If you wish to remove missing objects on the first synchronization onwards, set the 'Threshold Number' to 0.