Sforno on Numbers 13:18/ספורנו על במדבר י״ג:י״ח

1וראיתם את הארץ מה היא. If it is mostly populated in open cities or walled cities, like fortresses.

2ואת העם היושב עליה, to find out if the ecological conditions favoured successful settlement in cities. In other words, if sick people would be referred by their physicians to such cities and to such a climate to help them regain their health. They would judge this by the appearance of the inhabitants of such cities; if they appeared healthy, strong, of good posture, etc. They would also observe if the people were numerous, had large families, or if somehow they were few in numbers. Large numbers of people, and people looking strong and fit, would indicate that the climate was good and favoured large-scale settlement.