When a country is just starting to develop its economy, direct foreign investment by a large company can be very important to it.
What will hopefull happen is that the company will make a lot of investments in buildings and such that are needed to carry out production in the country. Beyond that, the company will surely increase the levels of employment in the economy, both in terms of direct employment for the company and in terms of a "multiplier." In the multiplier effect, the workers employed directly by the company will spend their money in ways that cause others to have jobs selling goods and services to those workers.
The company can reduce instability in the country by improving its economy and its living standards.