When a line on a graph is going up, what does that mean?

When the line on the graph is going up it means that there is a direct relationship between x and y, the two pieces of data that is being plotted. As x goes up y goes up also. We call this the gradient of the line. If it is going up there is a positive relationship between x and y.

That the graph has a positive gradient

The variable on the Y axis is increasing