This is the 3063rd most frequent French word.
naturelles
"Naturelles" means "natural" in English.
In this sentence, 'naturelles' is used as an adjective agreeing in gender (feminine plural) and number with the noun 'couleurs' to describe the inherent qualities of the flowers' colors.
Les couleurs naturelles des fleurs sont fascinantes.
The natural colors of the flowers are fascinating.
Here, 'naturels' (masculine plural form) describes the products, emphasizing their organic or unprocessed qualities.
Elle préfère les produits naturels pour cuisiner.
She prefers natural products for cooking.
In this context, 'naturelles' (feminine plural form) modifies 'formations' to denote that the formations of rocks originated in nature, without human interference.