To find the coordinates of point A, we are given that it lies on the y-axis, below the x-axis, and at a distance of 5 units from the x-axis. Let's break down the problem step by step to understand it better.

Step 1: Understanding the coordinate system
In a two-dimensional coordinate system, the x-axis represents the horizontal axis, and the y-axis represents the vertical axis. The point where the x-axis and y-axis intersect is called the origin, denoted as (0,0). The x-axis has positive values to the right of the origin and negative values to the left. Similarly, the y-axis has positive values above the origin and negative values below.

Step 2: Analyzing the given information
From the given information, we know that point A lies on the y-axis, below the x-axis, and at a distance of 5 units from the x-axis. This means that the x-coordinate of point A is 0, as it lies on the y-axis. Also, the distance from the x-axis is the y-coordinate of the point.

Step 3: Finding the coordinates of point A
Since the x-coordinate is 0, we can now focus on finding the y-coordinate. The distance from the x-axis is given as 5 units, and since point A lies below the x-axis, the y-coordinate will be negative.

Therefore, the coordinates of point A are (0, -5).

Step 4: Verifying the answer
To verify our answer, we can plot the point A on the coordinate system. We place the point at the intersection of the y-axis and the line that is 5 units below the x-axis. The resulting point will have an x-coordinate of 0 and a y-coordinate of -5, matching our answer.

Thus, the correct coordinates of point A are (0, -5), which corresponds to option 'D' as the correct answer.