Mexico and Guatemala are two separate countries with their own visa requirements. Visitors to Mexico must obtain a Mexican visa, unless they are citizens of a visa-exempt country. Visitors to Guatemala must obtain a Guatemalan visa, unless they are citizens of a visa-exempt country.
If you are planning to visit both Mexico and Guatemala, you will need to apply for a visa for each country. The visa requirements for Mexico and Guatemala can be different, so be sure to check the latest requirements before you apply for your visa.