الفصل صعب.

Because Arabic often uses a nominal sentence in the present tense, with no overt verb for to be.

So الفصل صعب literally looks like the class/term/chapter difficult, but it means The class/term/chapter is difficult.

In grammar terms:

• الفصل = the subject
• صعب = the predicate/description

If you wanted was, will be, etc., Arabic would use a verb such as كان.

This is very common in Arabic.

• الفصل is definite: the class/term/chapter
• صعب is indefinite as a predicate: difficult

In simple equational sentences like this, the subject is often definite, while the predicate is often indefinite.

So:

• الفصل صعب = The class is difficult
• not الفصل الصعب in this context

If you say الفصل الصعب, that usually means the difficult class or the difficult chapter, where الصعب is no longer the predicate of the sentence but an adjective modifying الفصل.

It is an adjective in form, but in this sentence it functions as the predicate.

So grammatically, it is describing الفصل, but it is not attached to it the way an attributive adjective would be.

Compare:

• الفصل صعب = The class is difficult
  
  • صعب is the predicate
• الفصل الصعب = the difficult class
  
  • الصعب is an adjective directly modifying الفصل

That distinction is very important in Arabic.

In Arabic, adjectives normally come after the noun they describe.

So if you are making a noun phrase, Arabic says:

• الفصل الصعب = the difficult class

not the other way around.

In your sentence, صعب also comes after الفصل, but here it is the predicate of the sentence:

• الفصل صعب = The class is difficult

So in either case, the descriptive word usually comes after the noun.

It would normally be:

الفصلُ صعبٌ

This can be read as al-faṣlu ṣaʿbun.

Those endings show that both words are in the nominative case:

• الفصلُ = subject, nominative
• صعبٌ = predicate, nominative

In everyday Arabic writing, these short vowels are usually omitted, so you often just see:

الفصل صعب

Because normal Arabic writing usually leaves out short vowels and most case endings.

So:

• صعبٌ
• صعبُ
• صعبَ
• صعبِ

may all appear simply as صعب in ordinary text, and the reader figures out the correct form from grammar and context.

In this sentence, the grammatical full form is صعبٌ, but in standard unvowelled writing it is just صعب.

Also, when pausing at the end of a sentence, speakers often do not pronounce the final case ending clearly, so it may sound more like ṣaʿb.

A careful pronunciation is:

al-faṣl(u)

A few things to notice:

• ال is pronounced al- here, because ف is a moon letter, so the l is pronounced.
• ص is an emphatic s sound, deeper and darker than English s.
• The cluster صل at the end may feel unusual for English speakers: faṣl.

So the word is approximately:

• al-faṣl

not afasal or fasil.

A careful pronunciation is:

ṣaʿb(un)

Important sounds:

• ص = emphatic s
• ع = the letter ʿayn, a sound English does not have
• final ب = b

For many learners, ع is the hardest part. You do not need to make it perfect immediately, but you should try not to ignore it completely.

So صعب is not just saab. It is closer to:

• ṣaʿb

with a distinct consonant in the middle.

It is masculine singular.

The noun الفصل is grammatically masculine, so the describing word/predicate also appears in masculine singular form:

• الفصل صعب = masculine singular

If the noun were feminine, the predicate would usually be feminine too. For example:

• المادة صعبة = The subject/course is difficult

So yes, gender agreement matters here.

Yes. Depending on context, فصل can mean things like:

• chapter
• classroom period / class
• term / semester
• season

So الفصل صعب could mean different things depending on the context, such as:

• The chapter is difficult
• The term is difficult
• The class is difficult

The grammar stays the same; only the context changes the meaning.

It is called a nominal sentence in Arabic, traditionally جملة اسمية.

It has two main parts:

• المبتدأ = the topic/subject
  here: الفصل
• الخبر = the comment/predicate
  here: صعب

So الفصل صعب is a very basic and important Arabic sentence pattern:

[definite noun] + [predicate]

This pattern is one of the first structures learners should get comfortable with.