The Spanish language is unique because although many words have the same literal definitions, sentence context can change word meaning. With prepositions, placement in sentences determines their definitions.

Phrases With "a"

The "a" in many verb phrases conveys no specific meaning. For example, it's used with a form the verb "ir" to express an event in the future, like "Yo voy a estudiar." The "a" is also used before a direct object that is a person: "Yo voy a llamar a mi amiga." The "a" can also assume its common definition, "to," in sentences like "Yo voy a la escuela" or "Yo voy a San Antonio." Some expressions involving time also depend upon "a": "La fiesta es a las nueve."

Uses of "en"

The "en" in Spanish sentences typically means "by," "on" or "in." It can convey location or place: "Yo estoy en el parque" or "El libro está en la mesa." Generalizations about subjects also use "en": "Mi amigo es bueno en matemáticas." With the verb "ir," "en" relays method of travel: "Yo voy en coche." In time expressions, "en" means "in": "Yo voy en el verano."