The word "gestalt" is not a remote viewing term, even though that is the place you will hear it most. It is, in fact, a psychological term which means the basic conceptual quality or basic aspect of any one thing. For example, "dew", "lake", "ocean", "sweat", "rain", "ice", etc., all have the gestalt of "water". If you were to add "gasoline", "bleach", and "oil" to that list, the basic gestalt would be "liquid".
Remote viewing starts off with the viewer getting the basic gestalts of the site, and then taking each gestalt individually and describing its individual qualities. So, a session might begin with the viewing finding that the target has the basic gestalts of "land", "water", and "manmade". The second step or stage in the remote viewing process is to first give an actual description of the "land" at the site, then the "water" aspect of it, and then describe the "manmade" aspect of the target. In this way, a picture of the target builds up in a pollution-free environment.
One way of understanding the word, "gestalt" is to say that it is the "---iness" of the target. That is, "the target has water-iness, land-iness, and manmade-iness to it."