Learn Hardcore Italian: L'articolo parla del suicidio.

Because lo is the masculine singular definite article used before words starting with certain consonants, including z, s + consonant, gn, ps, and also before vowels in its shortened form.

Full form: lo articolo
Correct contracted form before a vowel: l'articolo

So l'articolo means the article.

Examples:

l'amico = the friend
l'uomo = the man
l'articolo = the article

Why is it parla and not parlare?

Parla is the third-person singular form of the verb parlare in the present tense.

The infinitive is:

parlare = to speak, to talk

But in the sentence, the subject is l'articolo = the article, which is it in English. So you need the form meaning it talks / it speaks about:

io parlo = I speak
tu parli = you speak
lui/lei parla = he/she speaks
l'articolo parla = the article talks

So L'articolo parla... literally means The article talks...

Why does parlare use di here?