The problem is that some countries exploit other countries. For example, industrialized countries take advantage of poorer countries with cheaper labor, to get their goods cheaper. More powerful countries can take advantage of weaker ones in order to get them to produce the goods, and even services in this internet age, they need at cheaper prices.
Perhaps if you could be more specific as to what you need, we could be of more help. What is it you want to know about these inequalities?
In general, globalization only helps countries that already have some advantages. You have countries like China being helped because they already had a stable (if repressive) government and an educated population. Contrast that with many African countries that have not benefitted much from globalization. These countries lack stable government, educated populations, and basic infrastructure. This has made it much harder for them to benefit from globalization and has increased inequality in the world.
Neither Kuznets nor conventional theory, however, anticipated more recent studies analyzing the interrelationship between growth and inequality. In Kuznets’ hypothesis, inequality during the early stages of development was a regrettable but unavoidable, and ultimately worthwhile, price to pay. For its part, the Lewis surplus labour model supposed that the traditional sector (agriculture) is primarily important for supplying unlimited low-wage labour to the modern sector (industry) where increasing profits would be earned, thereby increasing inequality, and investment and capital accumulation would take pace, providing the engine of economic growth for the economy as a whole. Ultimately, the industrial (modern) sector would supersede the agricultural (traditional) sector, the supply of surplus labour would be exhausted, wages would rise with growing demand for industrial workers, and inequalities would fall.
penalizes poor countries by reducing their growth potential.Essentially, these critics reject the surplus labour model of accumulation, along with its simple two-sector characterization of the economy, in which only the modern sector can be the source of growth. Instead, they argue capital markets are highly imperfect, which results in considerable underinvestment, particularly when there are wealth and income inequalities, by those who are underendowed with assets and income.