What are the basic rules on un, une, l', le, la, etc?
Here are some basics:
Definite and indefinite articles are not interchangeable. In both English and French languages, their use is defined by rules, which are not always similar.
o DEFINITE ARTICLE "the" => l', le, la, les. As their name explains, they define nouns: the meal = le repas, is a specific meal, not any meal. Often, when you get longer sentences of a full text, you get hints by context. - ex: the woman eats THE meal that the cook prepared = la femme mange LE repas que le chef a préparé. - ex: the man, the friend and the water = l'homme, l'ami et l'eau -> le/la are changed to l' because of the following vowel or non aspired H
Note1: in English, when you claim a generality, like "men are stronger than women", the French use the definite article: "LES hommes sont plus forts que LES femmes".
o INDEFINITE ARTICLE "a/an" => un, une, des. In this case, the object is not defined, it is rather "one" thing out of several. - ex: the woman eats A meal three times a day = la femme mange UN repas trois fois par jour.
Note2: in English, "a/an" has no plural, whereas in French, the plural of UN/UNE is DES. - ex: the woman eats meals several times a day = la femme mange DES repas plusieurs fois par jour.
Basic rules ? Well... You have to first separate "le, la, l' "which are called "definite articles" in french from "du, de, des..." which are indefinite. Really basically, definite articles are used to talk about precise amounts, whereas the indefinite articles are more easily translated by "some" and equivalents. Definitely, "le, la" has "The" for equivalent. Maybe other members can help you out with that, but that's a start. Hope it could help.