**Explanation:**

To understand why the equation x = 0 represents the y-axis, we need to understand what the equation represents and how it relates to the coordinate plane.

**The Coordinate Plane:**
The coordinate plane is a two-dimensional graph that consists of two perpendicular lines called the x-axis and the y-axis. The x-axis is the horizontal line, and the y-axis is the vertical line.

**Equation:**
In mathematics, an equation is a statement that two mathematical expressions are equal. In this case, the equation x = 0 means that the value of x is equal to 0.

**Interpretation:**
When we have the equation x = 0, it means that x can only take the value of 0. This implies that the y-coordinate can take any value. In other words, for any point on the x-axis, the value of x is always 0, and the value of y can be any real number.

**Graphical Representation:**
To graph the equation x = 0, we plot all the points that satisfy the equation. Since x is always 0, the points on the graph will have an x-coordinate of 0. However, the y-coordinate can vary.

If we plot these points on the coordinate plane, we will find that they all lie on a vertical line passing through the point (0, 0). This vertical line represents the y-axis.

Hence, the equation x = 0 represents the y-axis.

**Summary:**
The equation x = 0 represents the y-axis because it means that for any point on the graph, the x-coordinate is 0, and the y-coordinate can be any real number. This corresponds to a vertical line passing through the point (0, 0), which is the y-axis.