Difficult words: undesirable (not desired -- wanted), manual labour (physical work), hail (call), face (deal with, or literally, use the face for something), garment (an item of clothing).
He might possibly have forgiven Julien his puny physique, ill adapted as it was to manual labour, and different as it was from that of his elder brothers; but he hated this reading mania.
If the temperature is so high that you can't work, can't do hard manual labour outside for significant parts of the year, then many places will become functionally no longer part of the economy.