Learn Italian: Questo articolo è per te.

After prepositions like per (for), you must use what are called "stressed" pronouns. For the informal "you", this form is te. You cannot use the subject pronoun tu here. (For example, "for me" is per me).

Does the preposition per always translate to "for"?

In this sentence, per shows who the article is intended for, which perfectly translates to "for". This is its most common meaning. You will also see it used to mean "in order to" or "through" in other contexts.

Since articolo starts with a vowel, shouldn't it be quest'articolo?

You can say quest'articolo, dropping the final -o of questo, but it is not mandatory for masculine words. Both quest'articolo and questo articolo are perfectly correct and widely used by native speakers.

Does articolo mean a written article or an item in a store?

It can be either! Just like the English word "article", articolo can refer to a piece of text in a newspaper or magazine, or to an individual item or product.