Снаружи уже были сумерки, а изнутри книжного магазина лился тёплый свет.

to be

Breakdown of Снаружи уже были сумерки, а изнутри книжного магазина лился тёплый свет.

• магазин: the store
• а: and
• уже: already

Questions & Answers about Снаружи уже были сумерки, а изнутри книжного магазина лился тёплый свет.

Why is there no word for it in Снаружи уже были сумерки?

Russian does not use a dummy subject like English it in sentences such as It was dark, It was late, or It was twilight.

So English It was already twilight outside becomes simply:

Снаружи уже были сумерки.

The idea is complete without any pronoun. Russian often leaves out a subject when English would use it only for grammar.

Why is сумерки plural, and why do we say были instead of было?

Сумерки is normally a plural-only noun in Russian. It refers to twilight / dusk, but grammatically it behaves like a plural noun.

So you say:

• были сумерки = it was twilight
• not было сумерки

This is similar to how some English nouns are formally plural, even when they refer to one idea, like scissors or pants.

Because сумерки is plural, the past-tense verb must also be plural:

• сумерки были

What does уже add here?

Уже means already.

In this sentence, it suggests that dusk had already set in by that point. It adds a sense of time progression:

• Снаружи были сумерки = Outside, it was dusk.
• Снаружи уже были сумерки = Outside, it was already dusk.

So уже helps create atmosphere: outside it had already grown dim, while inside there was warm light.