Increase (used as a verb or a noun):
This chart shows the increase in sales.
This chart shows how sales are increasing.
This chart show that sales are going to increase.
Growth (used only as a noun):
This chart shows the growth in sales.
Go up (used only as a verb, and generally only in the future tense):
This chart shows how sales are going to go up.
This chart predicts how sales will go up.
Rise (used as a verb OR a noun):
This chart illustrates the rise in sales.
This chart demonstrates how sales are rising.
This chart shows that sales are going to rise.
As you can see, rise and increase are synonyms.
Decline/fall/drop are all synonyms, and they are all antonyms to rise/increase. All three can be used as a verb or noun, just like their antonyms. Go down is an antonym to go up.
The parts of a graph:
X-Axis: the horizontal portion of a graph
Y-Axis: the vertical portion of a graph
Legend: a box containing explanatory text
Grid: the intersecting lines on the body of the graph
Units: the units in which data are displayed
In describing a rising trend on a graph, I would use increase/increasing, and for a falling trend, I would use decrease/decreasing. Those will keep you pretty safe.