هذا المبنى أعلى.

It is a nominal sentence in Arabic.

• هذا = this (masculine singular)
• المبنى = the building
• أعلى = higher / taller

So:

• هذا المبنى = this building
• أعلى = the predicate, describing it

A very literal breakdown is:

• this building higher

Natural English: This building is taller/higher.

Because in Arabic, the noun after a demonstrative is usually definite.

So:

• هذا المبنى = this building
• هذه السيارة = this car
• ذلك الرجل = that man

If you say هذا مبنى without الـ, that usually means This is a building, not this building.

So الـ is important here.

Because مبنى is a masculine singular noun in Arabic.

• هذا is used with masculine singular nouns
• هذه is used with feminine singular nouns

So:

• هذا المبنى = this building
• but هذه البناية = this building if you use the feminine noun بناية

Arabic demonstratives must match the noun's gender and number.

In Arabic, the verb to be is usually not stated in the present tense.

So Arabic often says:

• هذا المبنى أعلى
• literally: this building higher

But the meaning is:

• This building is higher/taller

This is completely normal Arabic.

If you wanted a past-tense sentence, then Arabic would normally use a verb such as كان:

• كان هذا المبنى أعلى = This building was taller/higher

أعلى is an elative form, often used for comparative or superlative meanings.

Depending on context, it can mean:

• higher
• taller
• sometimes highest / tallest

In this sentence, it most naturally means higher or taller.

For a building, English might choose either one depending on context.

If you wanted just high/tall rather than higher/taller, you would usually use another adjective, such as:

• عالٍ = high / tall
• مرتفع = high / elevated

So:

• هذا المبنى عالٍ = This building is tall/high
• هذا المبنى أعلى = This building is taller/higher

Because here أعلى is the predicate of the sentence, not part of the noun phrase this building.

So the structure is:

• هذا المبنى = the thing being talked about
• أعلى = what is being said about it

If you add الـ, you get a different kind of structure:

• المبنى الأعلى = the taller/higher building or the tallest/highest building, depending on context

So:

• هذا المبنى أعلى = This building is taller/higher
• هذا المبنى الأعلى would not mean the same thing

Arabic can leave the comparison understood from context.

So هذا المبنى أعلى can mean something like:

• This building is taller
• This building is higher
• with the comparison implied

If you want to say than explicitly, use من:

• هذا المبنى أعلى من ذاك المبنى = This building is taller than that building
• هذا المبنى أعلى من ذلك = This building is taller than that

So من is the normal word for than after this kind of comparative.

A helpful pronunciation guide is:

• هذا = hādhā
• المبنى = al-mabnā
• أعلى = aʿlā

Whole sentence:

• hādhā al-mabnā aʿlā

Two useful notes:

• The final ى in المبنى is pronounced like a long ā, not like English y
• The symbol ʿ in aʿlā represents the Arabic letter ع, which has no exact English equivalent

No. In this word, the final ى is alif maqṣūrah, and it is pronounced like a long ā sound.

So:

• المبنى is pronounced al-mabnā, not al-mabni

This spelling is common in some Arabic words, especially ones historically related to roots ending in ي or ى in their written form.

For a learner, the main thing to remember is:

• final ى often sounds like ā

Usually, in ordinary comparative use, words like أعلى stay in the masculine singular form, even if the noun being described is feminine.

For example:

• هذه البناية أعلى = This building is taller/higher

So unlike many ordinary adjectives, the comparative form often does not change here.

That is why you will also see things like:

• هذه أجمل = This one is more beautiful
• هي أكبر = She/it is bigger

This is a very common pattern with Arabic comparatives.