Осенью я редко ношу сапоги, но сегодня без них было бы неуютно.

Осенью is the normal way to say in autumn / during autumn.

Russian often uses the instrumental case with seasons as an adverbial time expression:

• весной = in spring
• летом = in summer
• осенью = in autumn
• зимой = in winter

So Осенью я редко ношу сапоги literally means In autumn, I rarely wear boots.

В осени is not how Russian normally expresses this idea.

Because носить means to wear in the sense of having something on regularly or habitually, while надевать means to put on.

Compare:

• Я ношу сапоги зимой. = I wear boots in winter.
• Я надеваю сапоги сейчас. = I’m putting on boots now.

In this sentence, the speaker is talking about a general habit in autumn, so ношу is the right choice.

Russian can use the singular сапог, but when talking about footwear people usually use the plural, because you normally wear a pair.

So:

• сапог = one boot
• сапоги = boots / a pair of boots

This is very common with clothing items worn in pairs:

• ботинки = shoes/boots
• туфли = shoes
• носки = socks
• перчатки = gloves

So ношу сапоги is the natural way to say wear boots.

It is accusative plural.

The verb носить takes a direct object, so сапоги must be in the accusative:

• Я ношу сапоги.

For inanimate plural nouns, the accusative is often the same as the nominative, so:

• nominative plural: сапоги
• accusative plural: сапоги

That is why the form does not visibly change.

After без (without), Russian uses the genitive case.

The pronoun они changes like this:

• nominative: они = they
• genitive after a preposition: них = of them / without them

So:

• без них = without them

A very important detail: many third-person pronouns get an extra н- after prepositions:

• у него
• с ней
• для них
• без них

That is why it is без них, not без их.

Yes, it could.

• ...но сегодня без сапог было бы неуютно.
• ...но сегодня без них было бы неуютно.

Both are grammatically correct.

But once сапоги has already been mentioned, using них is more natural and less repetitive, just like English often prefers them instead of repeating boots.

Было бы expresses a hypothetical / conditional idea: would be.

The meaning is:

• today, without them, it would be uncomfortable

The speaker is implying that they are wearing the boots today, or at least that going without them is not a good option.

Russian forms this kind of conditional with:

• past tense form + бы

So:

• было бы = would be

Compare:

• Сегодня без них неуютно. = Today it is uncomfortable without them.
• Сегодня без них было бы неуютно. = Today it would be uncomfortable without them.

The second version is more hypothetical.

Because in Russian, the conditional mood is built with a past-tense form + бы, even when the meaning is about the present or future.

So было бы does not mean the situation is in the past here. It means:

• would be now
• would be in this situation

This is completely normal in Russian:

• Я бы пошёл. = I would go.
• Это было бы трудно. = That would be difficult.
• Сегодня без них было бы неуютно. = Today without them it would be uncomfortable.

There is no normal subject here. This is an impersonal construction.

The word неуютно is a predicative word meaning something like uncomfortable / not cozy / unpleasant in terms of comfort. Russian often uses such words without a subject:

• Здесь холодно. = It is cold here.
• Мне грустно. = I feel sad.
• Без них было бы неуютно. = Without them it would be uncomfortable.

In these impersonal sentences, the past-tense verb usually appears in the neuter singular:

• было

So the neuter form does not refer to a noun; it is just the normal form in this structure.

Неуютно literally relates to a lack of comfort, coziness, or physical ease.

In this sentence, it most likely means something like:

• it would feel uncomfortable
• it wouldn’t feel comfortable
• it would be unpleasantly chilly/wet without them

Because the sentence is about boots, неуютно suggests physical discomfort due to the weather or conditions, not necessarily emotional discomfort.

No, they do different jobs:

• Осенью gives a general time frame: in autumn, as a rule
• сегодня introduces a specific exception: today

So the structure is:

• Usually in autumn, I rarely wear boots
• but today, without them, it would be uncomfortable

This contrast is one of the main points of the sentence.

Russian word order is flexible, and this placement highlights the condition:

• без них = without them

By putting it early, the sentence emphasizes that the lack of the boots is what would cause the discomfort.

A more English-like logic is:

• but today, without them, it would be uncomfortable

So the word order is natural and helps the sentence flow from contrast (но сегодня) to condition (без них) to result (было бы неуютно).