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"Pegatinas" is a form of "pegatina", a noun which is often translated as "sticker". "Copa Mundial" is a noun which is often translated as "World Cup". Learn more about the difference between "Copa Mundial" and "pegatinas" below.
la Copa Mundial()
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
la pegatina()
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).