What is the primary function of the PROPCASE function?

The PROPCASE function is designed specifically to capitalize the first letter of each word in a string while converting all other characters to lowercase. This feature is particularly useful for formatting text where proper nouns and the beginning of sentences need to be highlighted, ensuring a standardized appearance that aligns with grammatical conventions.

For instance, if you apply the PROPCASE function to the string "hello world", the output would be "Hello World". This functionality makes PROPCASE a valuable tool in data preparation, especially in cases where the input data might not be consistently formatted.

The other options focus on entirely different functions: one deals with converting characters to lowercase, another with changing them to uppercase, and the last option relates to counting characters in a string, none of which align with the primary purpose of capitalizing the first letters of words.