هذه محاولة.

Because محاولة is a feminine singular noun.

In Arabic, demonstratives have to agree with the noun in gender:

• هذا = this for masculine singular
• هذه = this for feminine singular

So since محاولة is feminine, you say هذه محاولة.

In Arabic, the verb to be is usually not written or said in the present tense.

So هذه محاولة literally looks like this attempt, but it means:

This is an attempt.

This is a very common Arabic sentence pattern, called a nominal sentence.

If you wanted to say it in the past, then Arabic would use a verb, for example:

• كانت هذه محاولة = This was an attempt

It is a nominal sentence.

A simple way to understand it is:

• هذه = the subject, meaning this
• محاولة = the predicate, telling you what this is

So the structure is basically:

This + attempt

which in natural English becomes:

This is an attempt.

Because the meaning is an attempt, not the attempt.

In Arabic:

• محاولة = an attempt / attempt
• المحاولة = the attempt

So:

• هذه محاولة = This is an attempt
• هذه المحاولة = This is the attempt or this attempt

The sentence you have uses the indefinite form because the meaning is general, not specific.

In careful Modern Standard Arabic pronunciation, it is:

hādhihi muḥāwalatun

A few notes:

• هذه is pronounced hādhihi
• محاولة is pronounced muḥāwala in pause, or muḥāwalatun with full case ending

In normal reading, many speakers will stop at the end and say:

hādhihi muḥāwala

The dh sound in hādhihi is like the th in English this.

That is because of case endings and pause.

In fully vocalized, formal Arabic grammar, محاولة here is nominative and indefinite, so it would be:

مُحَاوَلَةٌ = muḥāwalatun

But in normal reading and speech, especially when stopping at the end of a sentence, the ending is usually dropped, so you hear:

muḥāwala

Both are connected to the same word. The fuller form shows grammar more explicitly.

It is feminine because it ends in ة , called tāʾ marbūṭa.

This ending very often marks feminine nouns in Arabic.

So:

• محاولة is grammatically feminine
• that is why it takes هذه

Also, many verbal nouns and abstract nouns in Arabic are feminine in form, and محاولة is one of them.

It is a noun, and more specifically it is a verbal noun meaning attempt or trying.

It comes from the verb:

حاول = to try / to attempt

So:

• حاول = he tried
• محاولة = an attempt / trying

This is very common in Arabic: a verb has a related noun that expresses the action as a thing or concept.

Yes, but it means something different.

• هذه محاولة = This is an attempt
• هذه المحاولة = This is the attempt or this attempt

Adding الـ makes the noun definite, so it refers to a specific attempt already known from context.

So the original sentence is correct if the intended meaning is This is an attempt.

In Arabic, it can function as a full sentence.

An English speaker may feel that it is only a phrase because there is no visible is, but in Arabic this is a complete and natural sentence in the present tense.

So yes, هذه محاولة is a full sentence meaning:

This is an attempt.

Yes. Depending on context, محاولة can refer to:

• an attempt
• an effort
• sometimes the idea of trying

In your sentence, the most natural translation is:

This is an attempt.

But in other contexts, it can have a slightly broader sense, like an effort to do something.

If the noun were masculine singular, you would usually use هذا instead of هذه.

For example:

• هذا كتاب = This is a book

Compare:

• هذه محاولة = This is an attempt
• هذا كتاب = This is a book

This helps show how the demonstrative changes to match the gender of the noun.