Remember that heritability is a ratio of specific variances

Question

How would I answer this question? I keep on misunderstanding what it is asking:

1. Remember that heritability is a ratio of specific variances (h² = V_A/V_P).  What does V_A represent? How does an increase or decrease in V_A influence the value of h²? What does V_P represent, and how does increase or decrease in environmental variation alter heritability? How do you think environmental correlation might have influenced the estimate of heritability (affecting V_A or V_P), and how might you design an experiment to avoid the problem?