please read the following paragraph.
I am sitting at an airport watching people in the final moments before their loved ones arrive or depart. They are pacing, nervous, looking at one another, touching and not touching. The emotion is intense.
What's the meaning of colored part? What does "touch" mean?
who touch whom or what?
Touch doesn't necessarly mean that you have fysical contant with another person. I think that "touching" is used as a gerand here and not as a verb. Just look at the last sentence -> The emotion is intense. So, "touching" here probably means that it is an "intense" or "touching" moment.
Seeing people saying goodbye or welcoming their loved ones is an emotional moment for them but it can also have an effect on you as viewer. So, an emotional moment is a touching moment ... it touches your feelings, emotions.