When Scheduled segmentation is completed and a new segment is created with Segment name and ID how to evaluate the segment using API?

Hello 

Let us say a scheduled segmentation is completed and marketer decides to do an on-demand segmentation with a Segment Name - New Segment

Segment ID - XXXXXX
Now he decides to evaluate the segment. 

By new segmentation does it mean an activity of segmentation to add or evaluate the existing segmentation?

What API call I should use to evaluate the segment? Post or Segment - Should I use Segment Name or ID?

I am new to AEP 

I went to following link 

https://experienceleague.adobe.com/docs/experience-platform/segmentation/api/segment-jobs.html?lang=en

However getting lost in understanding the meaning of evaluating the segment