This is the 1667th most frequent Spanish word.
plástico
Plastic.
In this sentence, 'plástico' is used as an adjective to describe the type of bags (made of plastic).
Las bolsas de plástico son muy comunes en las tiendas.
Plastic bags are very common in stores.
Here, 'plástico' functions as a noun referring to the substance itself.
El plástico es un material versátil y duradero.
Plastic is a versatile and durable material.
In this case, 'plástico' is again used as a noun, indicating a specific type of the material.