The "Y-Value" refers to the vertical coordinate in a two-dimensional graph, indicating the position of a point along the vertical axis. In a Cartesian coordinate system, each point is defined by an X-Value and a Y-Value, where the Y-Value represents how far up or down the point is located from the origin. In mathematical functions, the Y-Value is often dependent on the X-Value. For example, in the equation of a line, the Y-Value changes based on the X-Value input, illustrating the relationship between the two variables. This concept is fundamental in graphing and analyzing data.