What does “плотность населения” mean in Russian?

Плотность населения is Russian’s standard phrase for “population density” — how many people share a unit of land. You’ll meet it in textbooks, news reports, and census statistics, always followed by a figure: людей на квадратный километр, “people per square kilometre.” The phrase sticks fastest through an extreme case: Alaska’s density is roughly half a person per square kilometre, which is why farmers there fly light aircraft instead of driving to the nearest shop.

The clip states it plainly: из-за плотности населения, примерно пол человека на квадратный километр, новые магазины не появляются — “because of population density, roughly half a person per square kilometre, no new shops open up.” That absurd half-person figure is what makes the abstract term memorable. Плотность on its own means “density” or “thickness” (from плотный, “dense/solid”); населения is the genitive of население, “population.” In use, the noun phrase is neutral and formal — standard in geography class, demographic reports, and any news story about urban sprawl or rural decline.