Sentence Piece is a sub-word tokenization tool used in natural language processing. It is an unsupervised algorithm that can split words into smaller units, such as phrases or individual characters. The term 'CLAUSE' is used to refer to a group of words that form a meaningful unit within a sentence. A CLAUSE typically contains a subject and a verb, and may also include other elements such as objects, modifiers, and adverbs. Sentence Piece can be used to break down sentences into their component clauses, allowing for more accurate analysis of the text.