A sailboat has four basic components that allow it to sail. They are the hull, the sail(s), the keel or centerboard, and the rudder.
The hull is obviously designed to carry crew, equipment, rigging (mast, spars, etc.) and move through the water with ease.
The sails actually provide the force to make the boat move through the water. To imagine a sailboat going away from the wind or having the wind push on the sails is fairly straight forward. It is more difficult, however, to understand how a boat sails toward the wind. In actuality sailboats cannot sail directly into the wind. As mentioned above there is a "no go zone" in which the sails provide no power to move the boat; they simply flap in the wind.
The force that the wind transfers to the sails actually makes a boat move forward for much the same reason a plane flies. If you were to look down on a sailboat from a helicopter you would see what looks like an airplane's wing except standing on end. The air moving across the sails, like air moving across an airplane wing, creates lift.
The keel or centerboard keeps the boat from being pushed sideways by the wind. The resistance from the hull and the keel translate the lift to forward motion. You do also get some sideways motion or leeway.
The rudder is used to steer the boat. You may have an extension attached to the rudder called a tiller. When the tiller is moved to one side, the rudder moves and the force of water flowing over the rudder causes the boat to turn. You should remember that on boats with tillers, you must push the tiller in the opposite direction that you want to turn. On larger sailboats with wheel steering, the boat turns the same way that the wheel is turned.
Each direction that a sailboat sails has a name that describes it. All sailing terminology has been developed in order to quickly and succinctly communicate with the crew what procedures should be performed in order to sail the boat effectively. The closer to the wind the boat comes, the tighter the sails. Conversely, the further off the wind, the looser the sails.