Если новые ботинки натирают пятку, лучше надеть другие.

Because ботинки means boots/shoes and is normally used in the plural when talking about a pair.

• ботинок = one boot/shoe
• ботинки = boots/shoes, a pair

Russian often uses the plural for footwear that comes in pairs, just like English often says new shoes rather than a new shoe.

Because the subject is новые ботинки, which is plural, so the verb must also be plural.

• ботинки натирают = the boots rub/chafe
• ботинок натирает = the boot rubs/chafes

This is just normal subject-verb agreement.

Here натирать / натереть means to rub and cause irritation, especially with shoes or clothes against the skin.

So in this sentence, it means something like:

• to rub your heel raw
• to chafe your heel
• to cause a sore spot by rubbing

This is a very common verb with shoes:

• ботинки натирают = the shoes are rubbing/chafing
• туфли натёрли ногу = the shoes rubbed the foot raw

Because пятку is the direct object of натирают.

The basic pattern is:

• натирать что? = to rub/chafe what?

So:

• пятка = nominative
• пятку = accusative

Here the boots are acting on the heel, so Russian uses the accusative:

• ботинки натирают пятку

Since пятка is a feminine noun, the accusative singular ends in -у.

Russian often uses the singular for a body part when the meaning is obvious from context.

So натирают пятку means they rub your heel or they rub the heel, usually understood as one heel being the problem.

You could hear plural forms in other contexts, but singular is very natural here because people often talk about the specific spot that hurts.

Because Russian often leaves out possessive words like my, your, his, etc. when the owner is obvious.

In this sentence, if the boots are rubbing a heel, it is naturally understood to be your heel or one’s heel.

Russian prefers the shorter, more natural version:

• ботинки натирают пятку

rather than explicitly saying:

• ботинки натирают твою пятку

The version with твою is possible, but it sounds more specific or emphatic than needed here.

Here лучше works as an impersonal predicate meaning it is better.

So the structure is:

• лучше + infinitive = it is better to ...

Examples:

• Лучше подождать. = It’s better to wait.
• Лучше уйти сейчас. = It’s better to leave now.
• Лучше надеть другие. = It’s better to put on another pair.

Russian often omits the equivalent of English it is in this kind of sentence.

This is a very common learner question.

In standard Russian:

• надеть = to put on something
• одеть = to dress someone

So:

• надеть ботинки = to put on boots
• одеть ребёнка = to dress a child

Since the sentence means to put on another pair, надеть is the correct verb.

A classic rule many learners remember is:

• надеть что-то на кого-то
• одеть кого-то во что-то

Even native speakers sometimes mix these up in casual speech, but in standard usage надеть is right here.

Because the sentence is about a single complete action: put on a different pair.

• надеть = perfective, one completed action
• надевать = imperfective, repeated/process meaning

After лучше, both aspects can appear, but they mean slightly different things:

• лучше надеть другие = better to put on another pair now / in this situation
• лучше надевать другие = better to wear/put on different ones generally, as a habit or repeated choice

Here the perfective надеть fits the idea of practical immediate advice.

Because in Russian, adjectives can often stand on their own when the noun is obvious.

So другие here means:

• other ones
• another pair
• different ones

The omitted noun is understood from context as ботинки.

This is very natural in Russian:

• Мне нужны новые. = I need new ones.
• Возьми большие. = Take the bigger ones.
• Надень другие. = Put on different ones.

Because другие refers back to ботинки, which is plural.

So the implied full phrase is:

• надеть другие ботинки

Since ботинки is plural, the adjective must also be plural:

• другие ботинки

If the noun were singular feminine, then you would get другую, for example:

• надеть другую куртку = to put on another jacket

Because the sentence begins with a subordinate clause introduced by если:

• Если новые ботинки натирают пятку, ...

In Russian, clauses introduced by если are separated by a comma from the main clause.

So the structure is:

• Если X, Y. = If X, then Y.

This comma is required.

Yes. Russian word order is flexible, although the original version sounds very natural.

Original:

• Если новые ботинки натирают пятку, лучше надеть другие.

You could also say:

• Лучше надеть другие, если новые ботинки натирают пятку.

Both are grammatical. The difference is mostly in emphasis:

• starting with Если... sets up the condition first
• starting with Лучше... emphasizes the advice first

The original is a very normal, neutral way to say it.

Yes, but the meaning would become more specific or slightly different.

• ботинки = boots/ankle boots, sometimes sturdy shoes depending on context
• туфли = shoes, especially dress shoes
• обувь = footwear in general

So the choice of ботинки tells you the speaker is specifically talking about boots or boot-like shoes, not just footwear in general.

For example:

• Если новая обувь натирает пятку... = If the new footwear rubs your heel...
• Если новые туфли натирают пятку... = If the new shoes rub your heel...

All are possible, but ботинки is the noun chosen in this particular sentence.