Deadlines and intakes
There is no national application system for international students. Each university runs its own admissions, entrance exams and calendar, and Mexican public universities often use a competitive entrance examination. Admission also generally depends on having your previous studies recognised, a process called revalidación.
Work backwards from the visa: you need an admission letter before you can book a consular appointment, and you must reach Mexico and start the INM exchange within 30 days of entry. Allow at least three to four months between your admission letter and your start date.
Language you need
Most degree programmes are taught in Spanish. UNAM asks international mobility students for an official Spanish certificate at at least B2 under the Common European Framework, and full-degree applicants should expect similar or higher expectations. A small number of private universities and specific master's programmes teach in English; check the language of instruction for each course, not just the university.
You do not need Spanish for the visa, but the INM, banks, landlords and any job will be in Spanish.