The corrected sentence is "We've got fifteen kinds of kale for sale today!"
This sentence is incorrect because it does not follow the principles of the adjective-noun agreement. In other words, the word "fifteen" that is an adjective is plural but the word "kind" that follows the adjective is singular.
Since the adjective cannot be made singular, the best option is to change the noun to a plural noun. Therefore, change kind to kinds.
Learn more about adjectives in: https://brainly.com/question/11385993