Final answer:
The country bordered by Mexico to the north and west, Belize to the northeast, and El Salvador to the southeast is Guatemala, which is the most populated country in Central America.
Step-by-step explanation:
The country bordered by Mexico to the north and west, Belize to the northeast, and El Salvador to the southeast is Guatemala. Guatemala is a significant country in Central America with a diverse cultural heritage, and it is the most populated country in the region.
The official language spoken is Spanish. Guatemala is known for its rich history, part of the Mesoamerican cultural area, encompassing advancements in calendar systems and agriculture.