Папа насыпал уголь в мангал, а я подала ему шампуры.

Because папа is one of the common Russian nouns for a male person that looks like a first-declension noun but is still masculine in agreement.

So you say:

• папа насыпал = Dad poured in / put in
• not папа насыпала

The ending -а does not automatically make a noun feminine in Russian.

They show the gender of the subject in the past tense.

• насыпал = masculine past singular
• подала = feminine past singular

So:

• Папа насыпал tells you the subject is masculine.
• я подала tells you the speaker is female.

If the speaker were male, it would be я подал.

Both verbs are perfective:

• насыпать / насыпать? In this sentence, насыпал is from perfective насыпать in the sense of to pour in / add a quantity
• подала is from perfective подать

Perfective is used because the sentence presents the actions as completed events:

• Dad finished putting the charcoal into the grill.
• I finished handing him the skewers.

If you used imperfective, it would sound more like describing an ongoing process or repeated action.

Here уголь is the direct object, so it is in the accusative case.

But for an inanimate masculine singular noun, the accusative often looks exactly like the nominative. So:

• nominative: уголь
• accusative: уголь

That is why you do not see a visible ending change here.

Because в can take different cases depending on meaning:

• в + accusative = motion into something
• в + prepositional = location in something

Here the charcoal is being poured into the grill/brazier, so Russian uses accusative:

• в мангал

Compare:

• уголь в мангале = the charcoal is in the grill
• насыпал уголь в мангал = poured charcoal into the grill

Ему is the dative case of он and means to him.

In я подала ему шампуры:

• ему = indirect object, the person receiving something
• шампуры = direct object, the thing being handed

So the structure is:

• подать кому? что?
• ему = to whom?
• шампуры = what?

Шампуры is the plural of шампур.

In this sentence it is the accusative plural direct object. Since шампур is inanimate, its accusative plural is the same as its nominative plural:

• nominative plural: шампуры
• accusative plural: шампуры

So the form does not change.

In this sentence, а is best understood as a kind of and, but with a slight sense of contrast, shift, or separate viewpoint.

• Папа насыпал уголь в мангал, а я подала ему шампуры.

This sounds like:

• Dad did one thing, and meanwhile / while I did another thing.
• It separates the two subjects: Dad vs I.

If you used и, it would sound more like simple addition:

• Папа насыпал уголь в мангал, и я подала ему шампуры.

That is also possible, but а is very natural when switching from one person’s action to another.

Because насыпать is the natural verb for putting in something that is loose, granular, or pourable, such as:

• sand
• sugar
• grain
• charcoal pieces

Положить means to put / place, and it works better for more solid, discrete objects.

So with уголь for a grill, насыпал sounds very natural: he poured/loaded in the charcoal.

Мангал is a brazier or charcoal grill, especially the kind used outdoors for cooking meat on skewers.

It is a very common word in Russian-speaking contexts, especially with foods like шашлык.

So мангал is not just any oven or grill in general; it usually suggests that specific metal charcoal grill/brazier.

Yes.

In Russian past tense, the verb agrees with the subject in gender if the subject is singular. So:

• я подал = I handed ... (male speaker)
• я подала = I handed ... (female speaker)

English does not show this, but Russian does.

Yes, Russian word order is flexible, but changing it changes the focus or emphasis.

The original order is very natural:

• Папа насыпал уголь в мангал, а я подала ему шампуры.

It presents the events clearly and neutrally.

You could rearrange parts, for example:

• Папа в мангал насыпал уголь, а я ему подала шампуры.

This is still understandable, but it may sound more marked or emphasize different parts.

For a learner, the original order is the best model.

A natural stress pattern is:

Па́па насы́пал у́голь в манга́л, а я́ подала́ ему́ шампуры́.

A few pronunciation notes:

• Папа = PA-pa
• насыпал = stress on сы
• уголь = stress on у
• мангал = stress on the last syllable
• подала = stress on the last а
• ему = stress on the last syllable
• шампуры = stress on the last syllable

Also, the comma before а is normal because it joins two clauses with different subjects:

• Папа ...
• я ...