غير رمل القطط في صندوق الرمل.

Here it is the verb غيّر meaning change! as a command.

That can be confusing because ordinary Arabic writing often leaves out short vowels, and sometimes learners also do not see the shadda clearly. So the spelling غير can represent different words.

In this sentence, the meaning is clearly the imperative verb because it is followed by the thing being changed.

Yes. This is an imperative sentence, so it is giving an instruction.

The subject is an implied you. Arabic usually does not state you separately in commands unless there is special emphasis.

The form shown is the normal singular command form. In learner-friendly terms, you can think of it as You, change...

A reasonable Egyptian-style pronunciation is:

ghayyar raml il-ʔoṭaṭ fi ṣondūʔ ir-raml

A few useful notes:

• غ sounds like a throaty gh
• ق in Egyptian Arabic is often pronounced as a glottal stop ʔ
• الـ before ر assimilates, so الرمل is pronounced more like ir-raml, not al-raml

Arabic often uses a noun-plus-noun structure called iḍāfa instead of using a separate word like of.

So:

• رمل القطط literally means litter/sand of the cats
• صندوق الرمل literally means box of the sand

English uses several patterns here:

• cat litter
• litter box
• the litter in the box

Arabic often prefers this compact noun-linking structure.

That is a basic rule of the iḍāfa construction.

In an iḍāfa:

• the first noun normally does not take الـ
• the second noun can take الـ
• the whole phrase gets its definiteness from the second noun

So:

• رمل القطط is correct
• صندوق الرمل is correct

Even though the first noun has no الـ, the whole phrase can still be definite because the second noun is definite.

English often uses a singular noun as a modifier, as in cat litter. Arabic usually does not do that in the same way here.

Instead, Arabic says something more like the litter of cats, so the plural القطط sounds natural. It refers to cats in general, not one specific cat.

If you were talking about one cat’s litter, you could say رمل القطة.

Yes, رمل literally means sand.

In this sentence, though, it refers to cat litter. That is a natural extension of the word because cat litter is a sand-like material. So even if the English meaning is shown as cat litter, the Arabic word is still literally sand.

في means in. It introduces the location phrase في صندوق الرمل.

The sentence order is:

• غيّر = verb
• رمل القطط = direct object
• في صندوق الرمل = location phrase

That is a very normal Arabic order: verb + object + place.

A little, yes, but context makes the intended meaning clear.

It can be understood as the location connected with the action: change the litter in the litter box.

Because that is the natural real-world reading, most speakers will understand it immediately the intended way.

Because that is how Arabic is normally written in everyday life.

Most Arabic text leaves out:

• short vowels
• many pronunciation details
• case endings

So learners have to rely on context and familiarity with patterns. That is why غير appears without full vowel marking even though the intended reading is غيّر.

It is understandable and acceptable in Egyptian Arabic, but it feels somewhat neutral or instructional rather than strongly casual.

An Egyptian speaker could absolutely use it, especially in a written instruction or a clear spoken command. In very casual speech, some people might choose slightly different wording or use a borrowed term for litter box, but the sentence itself is solid and clear.

A common Egyptian negative command would be:

ما تغيّرش رمل القطط في صندوق الرمل

The pattern ما ... ش is very common in Egyptian Arabic negation. So تغيّرش means don’t change.