Мясо мы решили замариновать вечером, чтобы утром быстро сделать шашлык.

Russian word order is much more flexible than English word order. Starting with мясо puts the meat in focus as the topic of the sentence.

A more neutral order would be:

Мы решили замариновать мясо вечером, чтобы утром быстро сделать шашлык.

By saying Мясо мы решили..., the speaker is highlighting the meat specifically, as if answering a question like What did we decide to marinate in the evening?

So мясо is still the object, even though it comes first.

Yes, решили already shows first person plural, so мы is not grammatically necessary.

Russian often omits subject pronouns when they are clear from the verb ending. But pronouns can be added for emphasis, contrast, or clarity.

Here, мы helps balance the fronted object:

Мясо мы решили...

This can sound a bit like:

As for the meat, we decided...

So мы is there for emphasis and natural flow, not because the sentence would be unclear without it.

After решить (to decide), Russian normally uses the infinitive:

• решили замариновать = decided to marinate

So the pattern is:

• решить + infinitive

Examples:

• Я решил поехать. = I decided to go.
• Мы решили приготовить ужин. = We decided to cook dinner.

You would not use a past-tense verb like мариновали after решили in this structure.

This is an aspect question.

• мариновать = imperfective
• замариновать = perfective

The imperfective мариновать refers to the process in a general or ongoing way:

• Я мариновал мясо весь вечер. = I was marinating meat all evening.

The perfective замариновать refers to completing the action:

• Мы решили замариновать мясо вечером. = We decided to marinate the meat in the evening (so that it would be properly marinated by the next stage).

In this sentence, the idea is a completed preparation step, so perfective замариновать is natural.

Сделать is the perfective form of делать. Here it is used because the purpose is to complete the action of making the shashlik.

The sentence means they want the meat ready in advance so that in the morning they can quickly get the shashlik made/prepared.

In purpose clauses with чтобы, Russian often uses the aspect that matches the intended result:

• чтобы утром быстро сделать шашлык = so that in the morning [we could] quickly make the shashlik

If the speaker wanted to emphasize process rather than completion, imperfective might be possible in other contexts, but here perfective is the most natural choice.

Russian often uses certain time words in the instrumental case without a preposition to mean in the morning, in the evening, during the day, etc.

So:

• утро → утром = in the morning
• вечер → вечером = in the evening
• день → днём = during the day / in the daytime
• ночь → ночью = at night

This is a very common pattern and should often be learned as a set expression.

Мясо is in the accusative case, because it is the direct object of замариновать.

However, мясо is a neuter inanimate noun, and for this type of noun the nominative and accusative forms are the same:

• nominative: мясо
• accusative: мясо

So even though the form looks unchanged, its function in the sentence is that of a direct object.

Шашлык is also in the accusative case, because it is the direct object of сделать.

For masculine inanimate nouns, accusative usually looks the same as nominative:

• nominative: шашлык
• accusative: шашлык

So in this sentence, шашлык is the thing being made.

After чтобы, Russian can use either:

• a finite verb
• an infinitive

The infinitive is common when the subject is understood from context and does not need to be repeated.

Here:

...чтобы утром быстро сделать шашлык

literally means something like:

...in order to quickly make shashlik in the morning

The subject is understood to be the same people, мы.

You could also see fuller structures in other sentences, for example:

• чтобы мы утром быстро сделали шашлык

That is more explicit, but here the infinitive is shorter and very natural.

Because чтобы introduces a subordinate clause of purpose.

Russian punctuation regularly separates the main clause from a subordinate clause with a comma:

• Мясо мы решили замариновать вечером, чтобы утром быстро сделать шашлык.

So the comma is required.

It is understandable and natural in colloquial Russian, especially in everyday speech.

However, depending on context, Russians may also say:

• приготовить шашлык = prepare/cook shashlik
• пожарить шашлык = grill/fry shashlik

Сделать шашлык is a broader, more conversational way to say make it / get it done.

So this sentence sounds quite natural, especially in informal speech.

Шашлык is a popular dish of marinated meat cooked on skewers, usually over coals. It is similar to kebab-style grilled meat, especially in post-Soviet cooking culture.

So in this sentence, the idea is:

they decided to marinate the meat in the evening so that in the morning it would be quick to prepare the skewered grilled meat.

Yes. A very neutral version would be:

Мы решили замариновать мясо вечером, чтобы утром быстро сделать шашлык.

This is probably the version many learners would expect first.

The original version:

Мясо мы решили замариновать вечером, чтобы утром быстро сделать шашлык.

is not strange, but it gives extra prominence to мясо. Russian speakers often move words around like this to match emphasis and information flow.