"Esto" is not masculine or feminine it is neutral. Masculine would be "Este" Femeneine "Esta". http://www.studyspanish.com/lessons/demonstratives.htm Each demonstrative pronoun also has a neuter form. They do not change for number or gender, and they are used to refer to abstract ideas, or to an unknown object.
esto (this matter, this thing) eso (that matter, that thing) aquello (that matter/thing over there)
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