The x-coordinate is a numerical value that represents a point's position along the horizontal axis in a two-dimensional space, such as a Cartesian coordinate system. It indicates how far left or right a point is from the origin, which is the point (0, 0). In a coordinate pair, the x-coordinate is listed first, followed by the y-coordinate, which represents the vertical position. For example, in the point (3, 2), the x-coordinate is 3, meaning the point is located three units to the right of the origin.