An "American two shot" shows the two heads facing each other in profile to the camera.
This enables both characters to appear together in a single shot directly facing the audience.
This framing is often used for shots of two people kissing or in moments of great dramatic tension.
Similarly, a three shot has three people featured prominently in the composition of the frame.
In contrast, the term "one shot" has another meaning: it is used to describe a whole film, sequence or scene captured in one continuous take, usually footage without actual or noticeable cuts.