says…
Se Pronoun realiza Verb anualmente Adverb en Adposition marzo Noun , en Adposition Buenos Aires 
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Pronoun
Verb
Adverb
Adposition
Noun
Adposition
It is held annually in March, in Buenos Aires. It is held annually in March, in Buenos Aires.
Words and sentences
se
-
- third person (also used for usted and ustedes) reflexive direct or indirect object oneself, himself, herself, itself, yourself; each other; one another
- used to convey the meaning of the English passive voice in the third person and with usted and ustedes
realiza
- inflection of realizar:
- inflection of realizar:
anualmente
yearly, annually (every year)
marzo
March
en
- in, at, on
- in (a time)
- in (a language)
- used after some verbs and translated by various prepositions in English
- in (in various expressions)
Buenos Aires
- Buenos Aires (the capital city of Argentina)
- Buenos Aires (a province of Argentina)
aires
plural of aire
buenos
masculine plural of bueno