أعرف هذا الأمر.

A careful full reading is aʿrifu hādhā l-amra.

A few notes:

• أعرف = aʿrifu
• هذا = hādhā
• الأمر = citation form al-amr, but after a preceding word it is usually pronounced l-amr in connected speech

The sound ʿ in aʿrifu represents the Arabic letter ع, which has no exact English equivalent.

If you stop at the end of the sentence, the final short vowel is often dropped in pause, so you may hear aʿrifu hādhā l-amr.

أعرف is the 1st person singular imperfect form of the verb عرف.

So it means:

• I know
• I recognize
• I am familiar with

In this sentence, it means I know.

The imperfect in Arabic can sometimes refer to present or future depending on context, but here it is naturally understood as present.

Because the verb already includes the subject.

أعرف by itself already means I know, so Arabic does not need a separate أنا.

You could say:

• أنا أعرف هذا الأمر

but that usually adds emphasis, contrast, or clarity, like I know this matter.

That أ is the normal prefix for 1st person singular in the imperfect tense.

So:

• أعرف = I know
• تعرف = you know or she knows (depending on context)
• يعرف = he knows
• نعرف = we know

The root of the verb is ع ر ف, which carries the basic idea of knowing or recognizing.

Because الأمر is a masculine singular noun.

In Arabic, demonstratives must agree with the noun in gender and number:

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

Since أمر is masculine, the correct form is هذا الأمر.

In standard Arabic, when a demonstrative like هذا comes before a noun, the noun is usually definite, so it normally takes الـ.

That is why Arabic says:

• هذا الأمر
• literally: this the-matter
• naturally in English: this matter

This is standard Arabic structure. English does not use the there, but Arabic usually does.

It is in the accusative case because it is the direct object of أعرف.

In fully vocalized Arabic, the sentence would be:

• أَعْرِفُ هٰذَا الْأَمْرَ

The final fatḥa on الأمرَ marks the accusative.

In normal everyday writing, short vowels are usually omitted, so you just see:

• أعرف هذا الأمر

Because هذا is an indeclinable demonstrative in standard Arabic. Its form stays the same here.

The whole phrase هذا الأمر functions as the object, but the visible case marking appears on the noun الأمر when vowels are written.

So in a fully vocalized form:

• هٰذَا stays هٰذَا
• الْأَمْرَ shows the accusative ending

الأمر is a common word with several related meanings, including:

• matter
• issue
• affair
• situation
• command/order in other contexts

In this sentence, it most naturally means something like:

• this matter
• this issue
• this affair

The exact English translation depends on context.

Not always.

A useful general distinction is:

• أعرف = I know / I am familiar with / I recognize
• أعلم = I know / I am aware of, often more about factual knowledge

So:

• أعرف هذا الأمر can suggest I know this matter or I’m familiar with this issue
• أعلم بهذا الأمر often means I am aware of this matter

In real usage, there can be overlap, but learners often find this distinction helpful.

In Modern Standard Arabic, the normal form is:

• هذا الأمر

Putting the demonstrative after the noun, as in الأمر هذا, is common in many spoken dialects, but it is not the standard MSA pattern for a sentence like this.

So for MSA, stick with:

• هذا الأمر

Yes, but Arabic allows some flexibility.

أعرف هذا الأمر is a normal and natural MSA sentence with the order:

• verb + object

You could also say:

• أنا أعرف هذا الأمر

if you want to make I explicit.

A more marked structure is possible for emphasis, but the version you have is the straightforward standard one.