بعد عشر دقائق أفتح الفرن وأضع الخبز على المائدة.

Because Arabic often puts a time expression first to set the scene: After ten minutes, ...

So:

• بعد = after
• عشر دقائق = ten minutes

Starting with this phrase is very natural in Arabic, especially in instructions, recipes, and step-by-step descriptions.

Here it means after ten minutes or ten minutes later.

It tells you that first there is a wait of ten minutes, and then the next actions happen:

• أفتح الفرن = I open the oven
• وأضع الخبز على المائدة = and I put the bread on the table

So this is a sequencing phrase, not a statement about how long the whole action takes.

Because numbers 3–10 in Arabic usually show gender polarity: the number takes the opposite gender of the counted noun.

Here the counted noun is دقيقة (minute), which is feminine.

So:

• feminine noun دقيقة
• masculine form of the number عشر

That is why Arabic says عشر دقائق.

After the numbers 3–10, the counted noun is normally:

• plural
• genitive

So Arabic says:

• عشر دقائق = ten minutes

not a singular form like عشر دقيقة.

This is just the standard pattern for numbers 3–10 in Modern Standard Arabic.

In Arabic, the present tense can also be used for:

• habitual actions
• instructions
• step-by-step narration
• near-future actions understood from context

In a recipe or procedure, Arabic often uses the present tense the way English might use either the present or the future:

• بعد عشر دقائق أفتح الفرن = After ten minutes, I open the oven

It sounds like a recipe step or a narrated sequence of actions.

The prefix أـ on a present-tense verb often marks first person singular: I.

So:

• أفتح = I open
• أضع = I put

The subject I is already built into the verb, so Arabic does not need a separate أنا here.

Because Arabic verbs usually already show the subject.

So أفتح already means I open, and أضع already means I put.

Adding أنا is possible, but it is usually only done for emphasis or contrast, such as:

• أنا أفتح الفرن، لا أنت = I open the oven, not you

In your sentence, أنا would be unnecessary.

Because the verb comes from وضع (to put/place), and this is a weak verb with و as its first root letter.

In the present tense, verbs of this type often drop that initial و in common forms:

• past: وضع
• present: يضع
• present, 1st person: أضع

So أضع is the normal correct form.

The preposition على means on or onto, so it fits the idea of placing bread on the table.

• على = on
• المائدة = the table / dining table

If you used إلى, that would usually mean to / toward, not on top of.

So:

• أضع الخبز على المائدة = I put the bread on the table

is the natural choice.

المائدة often means a dining table or table set for food. It fits very well in a food or serving context.

A learner may also know طاولة, which is a more general word for table.

So:

• المائدة = dining table / table spread with food
• الطاولة = table in a more general sense

In this sentence, المائدة sounds very appropriate because the bread is being placed where food is served.

The definite article الـ means the.

So:

• الفرن = the oven
• الخبز = the bread
• المائدة = the table

Arabic often uses definiteness when the objects are understood from the situation. In a cooking context, these are naturally the known oven, the bread being prepared, and the table being used.

A fully vocalized version is:

بعدَ عَشْرِ دَقائِقَ أفتَحُ الفُرنَ وأَضَعُ الخُبزَ على المائِدَةِ.

Some useful notes:

• بعدَ: accusative as an adverbial time expression
• عشرِ: genitive after بعد
• دقائقَ: genitive, but this plural is a diptote, so it shows fatḥa instead of kasra
• أفتحُ / أضعُ: present tense, indicative
• الفرنَ / الخبزَ: direct objects, so accusative
• المائدةِ: genitive after the preposition على

In normal unvowelled writing, these endings are usually not written, and in pause they are often not pronounced fully either.