if it’s a sailboat the wind will be behind them.

Sailboats are fastest when sailing across the wind, called a "Beam Reach"

Like the other person said this is a roll-on-roll-off cargo boat meaning it transports automobiles and cargo trailers. But I believe this specific one only does new cars.

As far as being aerodynamic, on a normal boat having things like biminis up can make docking difficult but with sail boats in general, a draggy top can hurt upwind performance. Meaning if you have some sleek aero superstructure then you might be able to sail 30° from the wind, but a bunch of biminis, a big square pilot house, etc might push you to 45° from the wind.

As an example, this boat might do 45° from the wind and exposed containers might push it to 55°, but that's still better than a lot of old ships which had terrible up wind performance.

There is a different one that's a retrofitted container ship with smaller sails. They do take up the space of a few containers but not many as far as I remember.

Edit: also every spec in this is just an example.