In poor countries, hunger is often caused, at least in part, by the fact that it is very hard to get goods from place to place. If there were better roads in the poor countries, this cause of hunger would be alleviated.
One thing that would help poor countries would be if their farmers could produce larger harvests. This would be more possible if the farmers had things like fertilizers. However, when farmers live in rural areas and there are no good roads, it is very hard to get fertilizers to them. Better roads would allow this to happen and would, thereby, increase harvests.
Another thing that causes hunger in poor countries is their inability to get food from the farmers to the population centers. Many kinds of food are rather perishable and need to be transported quickly. Without good roads, this is not possible. If there were good roads, food could easily be brought from the rural areas to the population centers and there would be less hunger in those cities.
In these ways, good roads would help to reduce the problem of hunger in poor countries.