To reach is to stretch toward something, arrive at a destination, or contact someone. You might reach for a bottle of water after you reach the finish line, then reach out to a friend who can give you a ride home.
Tall people often have a really long reach – they can practically grab something from across the room. If you do what your dad says long after he’s gone, his reach is long lasting. You can reach for a glass on a high shelf or reach the age you can get your driver's license. When people reach out, they try to make a connection, like an old phone company’s slogan: “Reach out and touch someone.”