Question

Could you explain and answer the question?

Answer 1

f(x) = f(6) means what is the value of y if x = 6.
You can see it on the graph for x = 6, y or f(x) = 4

Answer 2

So F(6) means 6 on the x axis then look to see where the graph is on the Y axis,

in this case on x 6 y=4