Before going out kitesurfing, you have to choose a good place to go that will have the right conditions for kiting- which begins with looking at the direction of the wind. Since offshore winds are bad for kiteboarding, you need to first look at the forecast to see the wind direction for the day, then choose a kiteboarding spot that will have side shore, side onshore, or onshore winds. Once again, offshore winds are off limits for kitesurfing unless you have a chase boat with you.
The arrows indicate the direction the wind is going based on North being at the top of the screen and West being at the left. This is opposite of what a typical weather vane shows, because they point into the wind, rather than the direction it is headed. Take a "Northerly" wind, for example. "North" is at the top of the screen (as maps generally have their northmost point at the top), and a "Northerly" is a wind that travels from the North to the South, so it is drawn as an arrow that points down - that is, pointing from North to South. Easterly Example: An easterly wind heads from the east (right side of the screen) towards the west (left side of the screen), so the arrow is drawn pointing to the left.