El titular de la portada es fácil de entender.

No. In this sentence, titular means headline.

That is different from título, which usually means title—for example, the title of a book, film, article, or chapter.

So in journalistic Spanish:

• titular = headline
• título = title

In Spain, titular is a very common word in news contexts.

Portada usually means front page or cover, depending on the context.

For example:

• in a newspaper, la portada = the front page
• in a magazine or book, la portada = the cover

So el titular de la portada means the headline that appears on the front page / cover.

They do two completely different jobs.

1. de la portada
   Here, de shows a relationship like of in English:
   the headline of the front page / the front-page headline

2. de entender
   Here, de + infinitive is part of the structure fácil de + infinitive, which means easy to + verb.

So:

• el titular de la portada = the front-page headline
• es fácil de entender = is easy to understand

Because Spanish usually uses definite articles more often than English.

• el titular = the headline
• la portada = the front page / the cover

Even if English might say something like Front-page headline is easy to understand in a headline style, normal Spanish generally keeps the articles:

• El titular de la portada...

In Spanish, the most common pattern here is:

• ser + adjective + de + infinitive

So:

• es fácil de entender = it is easy to understand
• es difícil de explicar = it is difficult to explain
• es imposible de creer = it is impossible to believe

You may sometimes hear es fácil entenderlo, but es fácil de entender is a very standard and natural structure.

Because the thing being understood is already clear from the subject:

• El titular de la portada ... es fácil de entender

The sentence already tells us what is easy to understand, so Spanish does not need to repeat it with lo.

If you added a pronoun, it would usually appear in a slightly different structure, for example:

• Es fácil entenderlo = It is easy to understand it

That is grammatical, but it is not the same structure as the original sentence.

Here fácil agrees with el titular, which is singular, so fácil is singular too.

However, fácil looks the same for masculine and feminine singular:

• el titular es fácil
• la noticia es fácil

The form only changes in the plural:

• el titular es fácil
• los titulares son fáciles

So gender does not change the form here, but number does.

Yes, that is grammatically correct.

Both are possible:

• El titular de la portada es fácil de entender.
• Es fácil de entender el titular de la portada.

The original version starts with the thing being talked about: the headline.

The second version starts with the comment about it: it is easy to understand.

The first version often feels a bit more straightforward in neutral written Spanish.

No. Spanish has a few ways to express that idea.

For example:

• el titular de la portada = the headline on the front page
• el titular de portada = front-page headline

Both can be natural, but they are not exactly identical in nuance.

• de la portada points more clearly to the headline of/on the front page
• de portada can sound a bit more like a category or label: a front-page headline

The original sentence is perfectly natural and very clear.

Because after de in this pattern, Spanish uses the infinitive.

The structure is:

• fácil de + infinitive
• difícil de + infinitive
• complicado de + infinitive

Examples:

• fácil de leer = easy to read
• difícil de ver = hard to see
• complicado de resolver = complicated to solve

So de entender means to understand in this construction.

It is general Spanish and would be understood everywhere.

That said, titular for headline is especially common and standard in Spain. It is also used in many other Spanish-speaking places, especially in journalism.

So a learner of Spanish from Spain should definitely know this word.

Yes, sometimes portada can also mean a main page or homepage, especially in media or publishing contexts.

For example, a news site may refer to its main page as la portada.

So depending on context, el titular de la portada could mean:

• the headline on the front page of a newspaper
• the headline on the main page of a news website

Without more context, both are possible.

It breaks down like this:

• El titular de la portada = subject noun phrase
• es = verb
• fácil de entender = predicate

So the pattern is:

• [subject] + ser + adjective + de + infinitive

A useful model sentence is:

• La explicación es fácil de seguir.
• El texto es difícil de traducir.

Your sentence follows exactly that pattern.