Learn Hardcore Spanish (Latin America): La revista publica un artículo nuevo cada mes. - The magazine publishes a new article every month.

Publica is the present indicative, and in Spanish the simple present is used to talk about habitual or repeated actions (what happens regularly). So La revista publica un artículo nuevo cada mes literally means “The magazine publishes a new article every month.”

If you said publicó, that would be the preterite (“published”) and refer to a single past event.
If you used publicará, that would be the future (“will publish”), indicating what the magazine is going to do, not a routine.

Why do we need the indefinite article un before artículo? Couldn’t we say publica artículo nuevo cada mes?

In Spanish, countable singular nouns almost always need an article (definite or indefinite). Without un, artículo sounds unfinished or ungrammatical. Here un artículo nuevo means “a new article” each time. If you used el artículo nuevo, you’d be referring to one specific “new article,” which changes the meaning.

Why is nuevo placed after artículo? Can I say un nuevo artículo?

Spanish adjectives typically follow the noun: artículo nuevo is the neutral, default order. You can say un nuevo artículo, but that slightly shifts the emphasis: putting nuevo before can convey an inherent or surprising newness (similar to “a brand-new article”). Both are correct; position just tweaks the focus.

What’s the difference between cada mes and mensualmente?

Both express “every month” or “monthly.”

cada mes is more common in everyday speech and literally means “each month.”
mensualmente is an adverb formed from mes (“month”) + -almente (similar to English “-ly”), and sounds a bit more formal or business-like.

Why is there no preposition before cada mes? In English we say “every month.”

Spanish uses cada directly before time expressions without a preposition. So you don’t need en or por. You simply say cada día, cada año, cada mes, etc., to mean “every day,” “every year,” “every month.”

Why isn’t there a se (like se publica) to make it passive?

There are two options:

Active voice: La revista publica… (The magazine publishes…)
Impersonal/passive: Se publica un artículo nuevo cada mes (“A new article is published every month” or “They publish a new article every month”).
In your example, the subject la revista is doing the publishing, so you don’t use se. You’d only add se if you wanted to avoid naming the subject or create a passive/impersonal construction.

Why is revista feminine and why la instead of el?

Spanish nouns ending in -a are usually feminine; revista (magazine) is one of them. The feminine definite article is la, so you say la revista (“the magazine”).