Given the problem:
Explain what are the figure below functions or not
The left graph is not a function, the right table is a function. To see if a graph is a function, use the vertical line test. Simply draw vertical lines down the graph, or you don't have to if you can imagine it. None of the vertical lines can pass through any points twice. So in this case, look at (6, 4) and (6, 6). Draw a vertical line down at x=6. It fails the vertical line test because the vertical line passes through the two points.
Next, the table on the right. It is a function. To determine whether a table is a function or not, look at the x values. No x value can duplicate. In this case, all x values are different.
Hope this helped.