* Le: This is the definite article meaning "the." (e.g., le livre - the book)
* Un: This is the indefinite article meaning "a" or "an." (e.g., un livre - a book)
* Mon, ton, son: These are the possessive adjectives meaning "my," "your" (singular informal), and "his/her/its," respectively. (e.g., mon livre - my book, ton livre - your book, son livre - his book)
* Notre, votre, leur: These are the possessive adjectives meaning "our," "your" (plural or formal singular), and "their," respectively. (e.g., notre livre - our book, votre livre - your book, leur livre - their book)
* Ce: This is a demonstrative adjective meaning "this" or "that." (e.g., ce livre - this book/that book)
* Quel: This is an interrogative adjective meaning "what" or "which." (e.g., quel livre? - which book?)
There are many other possibilities depending on the context, including other determiners, adjectives, and numerals. But the above are the most frequently encountered.