رتبي المائدة من فضلك، ولا تنسي الأطباق فوق الطاولة.

The verb forms show it.

• رتبي is the feminine singular imperative of رتّب.
• لا تنسي is the feminine singular negative command form of نسي.

So the speaker is talking to one female person.

If the speaker were talking to one man, the sentence would be:

رتّب المائدة من فضلك، ولا تنسَ الأطباق فوق الطاولة.

رتبي comes from رتّب, which means to arrange, organize, put in order.

With المائدة, it naturally means set the table.

So this is not just about putting things in order in a general sense. In this context, it specifically means arranging the table for a meal.

This is a very natural question, because both can be translated as table.

• المائدة often means the dining table or even the table as prepared for a meal.
• الطاولة is the more general word for a physical table.

So:

• رتبي المائدة = set the table
• فوق الطاولة = on top of the table / on the table

Using المائدة first gives a dining/meal-related sense, while الطاولة refers more to the object itself.

In Arabic, negative commands are usually made with:

لا + the present-tense verb in the jussive form

So here:

• و = and
• لا = do not
• تنسي = you forget in the form used after لا for a prohibition

A useful comparison is:

• أنتِ تنسين = you forget / you are forgetting
• لا تنسي = don’t forget

The final ن drops in this pattern.

So ولا تنسي literally works like:

and do not forget

It is the common polite expression for please.

Literally, it means something like from your kindness/favor, but in normal use it simply functions as please.

A useful detail for learners:

• to a man: من فضلكَ
• to a woman: من فضلكِ

In normal Arabic writing, short vowels are usually not written, so both appear as من فضلك. In this sentence, because the verbs are feminine singular, the intended reading is من فضلكِ.

Yes, فوق literally means above, over, or on top of.

In this sentence, though, English naturally says on the table, because the dishes are understood to be placed on its surface.

So:

• literal sense: above/on top of the table
• natural English in context: on the table

If you wanted a more neutral word for on, Arabic often uses على as well: على الطاولة.

It can mean either, depending on context.

• طبق can mean plate
• It can also mean dish
• In some contexts, it can even mean a course of food

Here, because the sentence is about setting the table, plates is probably the most concrete meaning. But dishes is also a perfectly natural translation.

To one man:

رتّب المائدة من فضلك، ولا تنسَ الأطباق فوق الطاولة.

To a group (masculine or mixed-gender plural in MSA):

رتّبوا المائدة من فضلكم، ولا تنسوا الأطباق فوق الطاولة.

So the command endings change depending on who is being addressed. That is one of the most important things to watch for in Arabic imperatives.