LOWER, UPPER and PROPER are text functions which let us do the following:
LOWER – Converts all words in the text to lowercase.
UPPER – Converts all words in the text to uppercase.
PROPER – Capitalizes the first letter in each word in the text.
All these functions use a single argument – The text we’d like to convert. This can be a text we type inside quotes, or we can just refer to another cell that contains the text.