I always get confused with "beve" and "bevi." I don't know why but I think "Tu beve aqua" makes more sense than "Tu bevi aqua." My native language is Spanish and I would likely accept if somebody explain to me how to use correctly in a sentence "beve" and "bevi," maybe I will understand it way better.
It is just a conjugation rule that is easy once you memorise it. Just use the correct ending depending on the subject (i.e. who you are talking about) and you will be using it correctly in a sentence. Here is the conjugation table for present tense "bere" (the first table under "presente"):
Although it is an irregular verb, because the "r" in "bere" changes to "v" when conjugated, it follows the same pattern as regular verbs ending in "ere" in terms of the endings:
actually the articles they use are from a grammar we don't have in English. This grammar is called "partitives". We don't say "je bois l'eau" (I drink the water) in English as well as the word "du" as in "je mange du pain" has no translation in English. Then, words like "du, de la, des, la and le" are not only articles, but partitives. Partitives are used with nouns that have no article.