Wing Planform

This is a well studied aerodynamic concepts but I’d like to give some info on how it changes what you could feel while foiling. the main terms you may hear are- Span, Area, Aspect Ratio, Sweep, and Lift Distribution. I'll cover the first 3 here and leave the 4th for another post.

Wing Span is pretty straightforward, the simplest way to explain what it does is it changes the balance of a wings glide and maneuverability. More span means more glide (lower induced drag) at the cost of turning and responsiveness (Roll rate and change in roll rate). This and the opposite effect are safe assumptions of a wing's performance independent of any other aspects of the design.

Area is the projected or surface area of the top view/planform/outline of a wing. There’s some debate in foiling on what area measurement is best, my opinion is projected area is preferable. it’s the most consistent because foil section or top/bottom surface measurement don’t affect the it.
For a given wingspan, more area lower your stall speed, acceleration, and top speed while increasing stability and low speed glide. 

Aspect ratio is in the simplest terms, how skinny or fat a wing outline is. It’s calculated using area and wingspan using- Span^2/Area.

Aspect ratio is a good indicator of high vs low speed performance, how forgiving a wing is to ride, and what you can expect to feel riding one. for a given wingspan. Per unit of area, a higher aspect ratio will be more efficient, with better glide and wider speed range. A lower aspect wing will turn better and generally have a more intuitive surfy feel. These are happy to just fly and aren’t as sensitive to changes in balance or water turbulence level.

Aspect ratio as a number probably isn’t that important to look at. It’s good to know the general shape and what high/low aspect is, but as numbers, knowing span and area will tell you way more. 

Personally, I consider 0-4 low aspect, 5-6 mid aspect, and <6 high aspect

Sweep mainly lowers the pitching moment and increases the stability and ease of use of a wing. Swept back wings tend to be very self correcting and can use a smaller tailwing for the same balance. The downside of sweep is increased drag due to spanwise flow and overloading of the tips at certain speeds. Many swept wings also handle ventilation poorly, but good design can eliminate it.