هو يخلط رزمة البطاقات.

Because Arabic verbs already include the subject, يخلط by itself can mean he mixes / he is mixing / he shuffles.

So هو يخلط رزمة البطاقات is perfectly correct, but هو is not strictly necessary. It is often added for:

• clarity
• emphasis
• contrast
  for example: هو يخلط، وأنا أوزّع = He shuffles, and I deal

So you could also say simply:

يخلط رزمة البطاقات

and it would still mean He is shuffling the deck of cards if the context is clear.

It can mean both, depending on context.

The form يخلط is the imperfect tense in Arabic. In English, that often matches:

• he shuffles
• he is shuffling
• sometimes even he does shuffle

Arabic does not force the same present simple vs. present continuous distinction that English does.

So:

• هو يخلط رزمة البطاقات can mean He shuffles the deck of cards
• or He is shuffling the deck of cards

Context tells you which is intended.

يخلط comes from the root خ ل ط, which has the basic idea of mixing or blending things together.

So the verb خلط / يخلط means:

• to mix
• to blend
• in the context of cards, to shuffle

That is why the same verb can be used in different situations, such as:

• يخلط الألوان = He mixes the colors
• يخلط الأوراق = He shuffles the cards/papers

Because this is an iḍāfa construction, often called a noun-noun possessive or “of” construction.

رزمة البطاقات literally works like:

• bundle/deck of cards

In an iḍāfa:

• the first noun normally does not take ال
• the second noun can be definite or indefinite
• the whole phrase is linked together

So:

• رزمة البطاقات = the deck of cards / a deck of cards, depending on context

You do not say الرزمة البطاقات for this meaning.

Because in an iḍāfa, definiteness is controlled by the second noun.

Here, البطاقات has ال, so it is definite. That makes the whole phrase definite as well:

• رزمة البطاقات = the deck of cards

This is a very common Arabic pattern:

• باب البيت = the door of the house
• كتاب الطالب = the student’s book
• رزمة البطاقات = the deck of cards

So even though رزمة itself has no ال, the whole phrase can still be definite.

In fully vocalized MSA, it would be:

هُوَ يَخْلِطُ رُزْمَةَ البِطاقاتِ

The important endings are:

• يخلطُ: the verb is in the indicative, so it ends in ـُ
• رزمةَ: this is the direct object, so it is accusative
• البطاقاتِ: this is the second part of the iḍāfa, so it is genitive

So grammatically:

• هو = subject pronoun
• يخلطُ = verb
• رزمةَ البطاقاتِ = object phrase

It is pronounced approximately yakh-liṭ in pause, or yakh-li-ṭu with the full ending in careful MSA.

A few pronunciation tips:

• خ is like the ch in German Bach or Scottish loch
• ط is an emphatic t
• the middle part is -li-, so the word is not yakhalat or yakhlat

A rough guide:

يَخْلِطُ = yakhliṭu

It can work, especially if the context is already clear, but it is a bit general because بطاقة often means card in a broad sense, like:

• ID card
• business card
• ticket/card

For actual playing cards, Arabic often uses expressions like:

• أوراق اللعب = playing cards
• ورق اللعب = playing-card paper/cards
• رزمة أوراق اللعب = a deck of playing cards

So رزمة البطاقات is understandable, but رزمة أوراق اللعب may sound more specifically like a real deck of playing cards.

Yes, but the meaning changes slightly.

• البطاقات = the cards
• رزمة البطاقات = the deck/pack of cards

So:

• هو يخلط البطاقات = He is shuffling the cards
• هو يخلط رزمة البطاقات = He is shuffling the deck of cards

Using رزمة makes it clearer that you mean the whole deck as a set, not just some cards in general.