Wheel and Deal turns a line consisting of two couples into a box consisting of two couples. There are two cases.

From a two-faced line, the two couples start turning toward each other, while starting to walk around each other. Each couple turns exactly halfway around (180 degrees), to face the opposite wall, and the couples end facing each other.

Note that the couples start turning in the same direction. From a right-handed two-faced line, they will both be turning to the right.

From a left-handed two-faced line, both couples will start by turning to the left. But they still end up facing each other.

From a one-faced line (with both couples facing the same direction), Wheel and Deal still ends in a box, but because all the dancers are turning halfway around they don't end up facing each other. Instead, the couple that started on the right wheels in front of the couple that started on the left.

You can think of this as the two couples starting to "pass right shoulders" as they both wheel toward each other.

Note that:

As with other actions involving four dancers, it is very common for two lines to be doing a Wheel and Deal at the same time. From parallel two-faced lines, each line will turn into a pair of facing couples.

From parallel one-faced lines facing out, back-to-back, the couple on the right in each line will end up in front of the other couple from their own line. They will end up in the center, facing the corresponding couple from the other line.