The question is very vague, but here's what it tells me.
We know that the coordinates are (4, 25) meaning the x is 4 and the y is 25.
Since time is x and height is y, all this is saying is this:
After 4 weeks, the corn stock is 25 inches.
You can go deeper and divide 25 by 4 to find out the rate of growth. That would give you 6.25, meaning
The corn stock grows 6.25 inches every week.