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"Marzo" is a noun which is often translated as "March", and "lunes" is a noun which is often translated as "Monday". Learn more about the difference between "marzo" and "lunes" below.
el marzo()
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
el lunes()
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).