Europe was affected in many ways by the economic expansion and increased trade that came along with the High Middle Ages. This is natural because any region is going to change if it becomes economically wealthier and engages in trade with distant lands.
Economic expansion makes a country (or in this case a region or continent) richer. This leads to higher standards of living. The higher standards of living in Europe were tremendously important during the High Middle Ages. Most importantly, the higher standards allowed for population growth. As agriculture boomed, more crops were grown. There were more kinds of food available and higher quantities of food. This allowed for tremendous population growth. Your text says that the population of Europe was about 36 million in 1000 C.E., but had grown to 79 million in 1300. This was the greatest impact of economic expansion.
Economic expansion and trade also brought about social change. Perhaps the most important impact was the rise of cities. Cities are only possible when an economy is strong. Farmers need to produce food surpluses to feed the people in the cities. Cities generally rely on trade because the people in the cities are producing goods that can be traded. This was the case in the High Middle Ages. Cities grew in places like Venice (trade with the Muslim world) and Flanders (trade with England and other parts of Europe). The cities also held a special place in the medieval world because they were generally wealthy enough to resist domination by any local lord or ruler. This made them independent.
Thus, economic expansion and trade had a tremendous impact on Europe. They allowed Europe to have a larger population. They allowed it to have higher standards of living. Long-distance trade brought new goods and new ideas to various areas of the region. The changes also allowed for the growth of cities, which helped make Europe begin to modernize both economically and socially.