To fully understand the path diagram (and all of its causal implications) from the study, you would need to have learned a series of concepts that draw relations upon eachother. For example, a mediator is present in the diagram and understanding what a mediator is, is crucial to interpreting the causal effects in the path diagram.

To understand all the implications of a mediator on the flow of effect on a causal diagram, one would first have to have a background in causal diagrams and how to interpret them. Additionally they are likely to need to have some background in the different causal junctions to know how to properly identify a mediator.

Furthermore to understand the mediators effects, one would have to know what regression and regression coefficients. Without such knowledge the person wouldn't know how to interpret the numbers on the arrow that indicate causal effect.