المحاولة صعبة.

Because Arabic usually leaves out the present-tense verb to be.

So المحاولة صعبة literally looks like the attempt difficult, but it means The attempt is difficult.

This kind of sentence is called a nominal sentence in Arabic. In the present tense, Arabic normally does not say a separate word for is / am / are.

الـ makes a noun definite, like the in English.

• المحاولة = the attempt
• صعبة = difficult

In this sentence, صعبة is the predicate adjective after the subject, so it stays indefinite.

That is why:

• المحاولة صعبة = The attempt is difficult
• المحاولة الصعبة = the difficult attempt (not a full sentence)

So the lack of الـ on صعبة helps show that this is a sentence, not just a noun phrase.

Because المحاولة is a feminine singular noun, and Arabic adjectives must agree with the noun they describe or refer to.

So:

• masculine: صعب
• feminine: صعبة

Since المحاولة is feminine, the adjective must also be feminine:

• المحاولة صعبة

This is grammatical gender, not biological gender. An abstract noun like attempt can still be grammatically feminine in Arabic.

Yes, that is a big clue.

The ending ة is called tāʾ marbūṭa, and it often marks a noun or adjective as feminine.

So learners will often recognize feminine words by this ending:

• المحاولة
• صعبة

Not every feminine noun uses this ending, and a few words with this ending behave unusually, but as a general rule, it is a very useful sign of feminine gender.

Usually, ة at the end of a word is pronounced like -a or -ah when you stop there.

So in normal paused pronunciation:

• المحاولة → al-muḥāwala
• صعبة → ṣaʿba

But in very careful reading with case endings, or when the word is connected in certain grammatical situations, the t sound appears:

• المُحاوَلَةُ
• صَعْبَةٌ

So the ة is written like a t, but often sounds like a at the end of an utterance.

In fully vowelled formal Arabic, it is:

المُحاوَلَةُ صَعْبَةٌ

Both words are in the nominative:

• المحاولةُ = the subject
• صعبةٌ = the predicate

In ordinary writing, those short vowels are usually omitted, so you normally just see:

المحاولة صعبة

In everyday reading or speech, many speakers also do not pronounce the full endings.

A practical pronunciation is:

al-muḥāwala ṣaʿba

A more careful full-form pronunciation is:

al-muḥāwalatu ṣaʿbatun

A few useful sound notes:

• ح in محاولة is a stronger, breathier h
• ص in صعبة is an emphatic s
• ع in صعبة is the Arabic letter ʿayn, a throat sound that English does not have
• In الـ, the l is pronounced here because م is a moon letter, not a sun letter

Yes. محاولة is related to the verb حاول, which means to try or to attempt.

So محاولة is a noun meaning something like:

• attempt
• trying
• an attempt

This is very common in Arabic: many nouns are built from verbs and express the action as a thing or event.

These are different structures:

• المحاولة صعبة = The attempt is difficult
  A full sentence.

• المحاولة الصعبة = the difficult attempt
  A noun phrase, not a full sentence.

• محاولة صعبة = a difficult attempt
  Also a noun phrase, but indefinite.

This is an important Arabic pattern:

• In a sentence, the predicate adjective is usually indefinite
• In a noun + adjective phrase, the adjective matches the noun in definiteness

So Arabic uses definiteness to help show the difference between sentence and description.

Yes, but المحاولة صعبة is the most neutral and straightforward order.

You may also see:

صعبةٌ المحاولةُ

This can be used for emphasis or a more literary style, something like Difficult is the attempt.

For a learner, the normal pattern to remember is:

• subject + predicate
• المحاولة صعبة

Then Arabic uses a form of كان:

• كانتِ المحاولةُ صعبةً = The attempt was difficult
• ستكون المحاولةُ صعبةً = The attempt will be difficult

Notice that كانت is feminine, because المحاولة is feminine.

Also, after كان and its forms, the predicate is formally accusative, so in full vowelled Arabic you get:

• صعبةً

But in normal unvowelled writing, you will usually just see:

• كانت المحاولة صعبة
• ستكون المحاولة صعبة