Yes a country can earn a lot of foreign exchange by exporting labor. If a country has sufficient population, they are not skilled, the government of that country should take adequate action plan to make them skilled. Many underdeveloped countries use this method to turn their manpower into public resources.
This is one of the efforts that must be made by the government of each country if they want their citizens to be smarter and more attractive to other countries in terms of more competent human resources. However, apart from that which must be an important point for the government, other things also need to be considered by the government such as a good economic sector and also an adequate level of infrastructure development to facilitate access for its citizens when they want to do something or want to learn about something more useful.