平和な丘や田園地帯から、通りがあり群衆がいる忙しい世界へと移動するのである。

、。

One moves from peaceful hills and countryside into a busy world of streets and crowds.

Literal

Peaceful hills [and-や] rural-areas [from-から], streets exist crowds exist busy world [to-へと] move [explanatory-のである].

や links 丘 and 田園地帯 as a non-exhaustive list ('hills and such'). へと is an emphatic directional particle — stronger than plain へ. のである closes the sentence with an explanatory, almost essayistic tone. The contrast between 平和な (peaceful) and 忙しい (busy) worlds is the structural point.