You are given a graph of two straight lines, and asked to say "where the product of the two straight lines will be zero, positive and negative", by which I would guess they mean "the x-values for which the product of the corresponding y-values will be zero, positive, or negative".
For a product of two values to be positive, what must be the signs on the two numbers? For a product of two values to be negative, what must be true of the two signs? For a product of two values to be zero, what must at least one of the values be?
Use this information to figure out the intervals of sign on the graph, keeping in mind that "on the x-axis" means that y is zero, "above the x-axis" means y is positive, and "below the x-axis" means y is negative.