Segmentations operate as a waterfall - whichever Segment the leads FIRST qualifies for, will be that Person's segment until their underlying data value changes.
From the way you word your question, I don't entirely get the mapping you want for
From Email Address | Segment Name
but let's say that you want
Josh.email@example.com | Colombia
and my Country value = Colombia
then that should be ok as long as your Segment is only looking at Country=Colombia.
Now, your Sample Test when you send it must be based off a Lead that matches your expectations. The best way is to right click on the asset and then add the email address of a Lead you wish to test against. In your case, you could test a Lead you KNOW has the Colombia Segment. Or just choose anyone and verify it later in the Lead Database.
But all of this assumes you have good data in your Segmentation and you understand the order of the waterfall.
For example, if you have two Country fields:
and in your Segment, you have Argentina > Colombia
and your Segment for Argentina says
then this Lead matches Argentina Segment.