В этой булочной мы иногда покупаем кофе и круассаны перед работой.

Because after в when you mean a location (in / at), Russian uses the prepositional case.

So both words change form:

• эта → этой
• булочная → булочной

A useful detail: булочная is one of those feminine nouns that decline like an adjective, so its prepositional form is булочной. Compare:

• в этой булочной
• в этой столовой
• в этой парикмахерской

So в этой булочной means in/at this bakery.

Булочная means bakery or bread shop.

In real life, it can mean:

• a shop that sells bread and baked goods
• sometimes a small bakery-café type place, depending on context

It is also a useful word to remember because it behaves grammatically like words such as столовая and парикмахерская.

Покупаем is the 1st person plural present tense of покупать.

• покупать = imperfective
• покупаем = we buy / we are buying

In this sentence it describes a habitual, repeated action: something we do sometimes.

That is why imperfective is natural here. Russian uses the imperfective for repeated or regular actions.

Compare:

• мы иногда покупаем = we sometimes buy
• мы купим = we will buy / we’ll buy once (future, perfective)

Yes. Russian often omits subject pronouns when the verb already makes the subject clear.

Because покупаем already means we buy, you could say:

• В этой булочной иногда покупаем кофе и круассаны перед работой.

But including мы is also completely normal. It can make the sentence:

• a bit clearer
• a bit more explicit
• slightly more contrastive, depending on context

So both are possible.

Because кофе is usually treated as an indeclinable noun in standard Russian. Its form often stays the same in different cases.

So you get forms like:

• люблю кофе
• пью кофе
• нет кофе

In standard grammar, кофе is traditionally masculine, even though it ends in -е.
In colloquial speech, some people treat it as neuter, but learners are usually taught that кофе is masculine.

Круассаны is the plural of круассан.

Here it is the direct object of покупаем. Since круассан is an inanimate noun, the accusative plural is the same as the nominative plural:

• singular: круассан
• plural: круассаны

So:

• покупаем круассаны = we buy croissants

If it were an animate noun, the accusative plural would usually look different.

Because the preposition перед takes the instrumental case.

So:

• работа → работой

That gives:

• перед работой = before work

This is very common:

• перед уроком = before class
• перед встречей = before the meeting
• перед сном = before sleep / before bed

Here it means time: before work.

The preposition перед can mean either:

• before (time)
• in front of (place)

But with работой, the natural meaning here is temporal:

• перед работой = before work, before going to work, or before the workday starts

Context makes that clear.

Because adverb placement in Russian is fairly flexible, and this is a very natural position.

Иногда often appears:

• before the verb
• after the subject
• sometimes at the beginning of the sentence

All of these are possible:

• Мы иногда покупаем кофе и круассаны.
• Иногда мы покупаем кофе и круассаны.
• Мы покупаем иногда кофе и круассаны. — possible, but a bit less neutral

The version in your sentence sounds natural and neutral.

No. Russian word order is much more flexible than English word order.

Your sentence starts with В этой булочной to set the scene first:

• In this bakery, we sometimes buy...

You could also say:

• Мы иногда покупаем кофе и круассаны в этой булочной перед работой.

That is also grammatical. The difference is mainly emphasis, not basic meaning.

Current order highlights the place first.

Because Russian has no articles.

So Russian does not have direct equivalents of English a/an and the.

Instead, Russian shows definiteness through:

• context
• word order
• demonstratives like этот / эта / это / эти

In this sentence, этой already helps specify the bakery as this bakery, so no article is needed.

A helpful stress pattern is:

В э́той було́чной мы иногда́ покупа́ем ко́фе и круасса́ны пе́ред рабо́той.

Main stressed syllables:

• э́той
• бulóчной
• иногда́
• покупа́ем
• ко́фе
• круасса́ны
• пе́ред
• рабо́той

A few pronunciation tips:

• булочной sounds roughly like boo-LOCH-noy
• покупаем sounds like pa-koo-PA-yem
• круассаны has stress on -са-

If you want, I can also break the whole sentence down word by word with pronunciation help.