It is possible to express nearly the same idea in English with "I like to wear a skirt" but that tends to imply some sort of circumstance (a skirt as opposed to something else). The plural makes the statement generic ( no one would take the meaning to be "multiple skirts at the same time"). Overt marking of number (singular or plural) is a required feature in English nouns but not in Vietnamese nouns. The plural in the translation depends on English grammar and idiom. Vietnamese has no plural noun form as such.