Это сандалии, в которых удобно ходить весь день, даже если ты не любишь каблуки.

In Russian, это is very often used as a fixed word meaning this is / these are. It does not change for number here.

So:

• Это сандалия. = This is a sandal.
• Это сандалии. = These are sandals.

Even though сандалии is plural, это stays the same.

Сандалии is the normal plural form, and in real life people usually talk about sandals as a pair, so the plural is very common.

The singular is сандалия, but you will hear the plural much more often in everyday use, especially in descriptions of footwear.

This is similar to how some clothing items are naturally thought of as a pair or set.

В которых means in which or more naturally here that you can walk in.

The full phrase:

• сандалии, в которых удобно ходить

  literally means:

• sandals in which it is comfortable to walk

In more natural English, that becomes something like:

• sandals that are comfortable to walk in

Russian often uses в которых with clothes and shoes where English would put the preposition at the end:

• ботинки, в которых удобно ходить = boots that are comfortable to walk in
• платье, в котором жарко = a dress that is hot to wear

Because the pronoun который has to match both:

1. the noun it refers to
2. the case required by its role in the clause

Here it refers to сандалии, which is:

• plural
• inanimate
• feminine in singular, but here plural matters most

And because of the preposition в, the pronoun must be in the prepositional case:

• которые = nominative plural
• которых = prepositional plural after в

So:

• в которых = in which

This is one of the most common uses of который in relative clauses.

Yes, in English we usually say on your feet or walk in sandals, but Russian commonly uses в with footwear and some clothing.

So Russian says:

• в сандалиях
• в ботинках
• в туфлях

literally in sandals / in boots / in shoes

This is just the normal Russian way to express wearing that kind of item.

Because удобно here is not describing the sandals directly as an adjective. It is part of an impersonal construction:

• удобно ходить = it is comfortable to walk

So the structure is roughly:

• в которых удобно ходить = in which it is comfortable to walk

If you said удобные сандалии, then удобные would be an adjective directly modifying сандалии:

• удобные сандалии = comfortable sandals

Both are possible, but they mean slightly different things structurally:

• Это удобные сандалии. = These are comfortable sandals.
• Это сандалии, в которых удобно ходить. = These are sandals that are comfortable to walk in.

The second version focuses more on the experience of wearing them.

Because ходить is the right verb for walking in general, walking around, or being able to walk for a period of time.

Compare:

• идти = to be going, to be walking in one direction, right now
• ходить = to walk generally, habitually, around, back and forth, over time

Here the sentence means that the sandals are comfortable for walking throughout the day, not for one single trip in one direction. So ходить fits much better.

• удобно идти would sound more like comfortable to be walking/go along right now
• удобно ходить весь день = comfortable to walk all day

Весь день is in the accusative case, and here it expresses duration of time:

• весь день = all day
• всю ночь = all night
• всю неделю = all week

Russian often uses the accusative without a preposition to show how long something lasts.

So:

• ходить весь день = to walk all day

This is very common and natural.

Даже если means even if.

Compare:

• если = if
• даже если = even if

So:

• если ты не любишь каблуки = if you don’t like heels
• даже если ты не любишь каблуки = even if you don’t like heels

Adding даже makes the contrast stronger: these sandals are comfortable even for someone who normally doesn’t like heels.

Ты is the informal singular you.

In Russian, product descriptions and advertising can sometimes use ты to sound:

• direct
• friendly
• conversational

If the speaker wanted to be more formal or polite, they could say:

• даже если вы не любите каблуки

That would also be perfectly correct.

So this is more about tone and style than grammar.

Because каблуки means heels, and in this context it refers to high-heeled shoes / heels in general.

Russian often uses the plural to talk about a type of footwear or a general category:

• любить каблуки = to like wearing heels
• не любить каблуки = to not like heels

This does not mean someone likes individual shoe heels as objects. It means they do or do not like that style of shoe.

Literally, каблук is heel. But in many everyday contexts, especially about fashion or shoes, каблуки can mean:

• heels
• high heels
• heeled shoes

So in this sentence, не любишь каблуки is best understood as:

• you don’t like wearing heels
• you’re not a fan of high heels

The exact English wording depends on context.

Russian usually does not use a present-tense verb equivalent to is/are in sentences like this.

So:

• Это сандалии literally looks like This/these sandals
• but it means These are sandals

And in the relative clause:

• в которых удобно ходить

  there is no separate word for it is. Russian often uses compact impersonal constructions like this.

A very literal breakdown would be:

• Это сандалии = These are sandals
• в которых удобно ходить весь день = in which [it is] comfortable to walk all day

This is completely normal Russian grammar.

Yes. A simpler version might be:

• Это удобные сандалии, в которых можно ходить весь день.

That means:

• These are comfortable sandals that you can wear/walk in all day.

The original sentence is a bit more polished and natural for a description. It emphasizes comfort in a smooth, descriptive way:

• в которых удобно ходить = that are comfortable to walk in

So the original sounds very natural for advertising, product copy, or recommendation language.

It breaks down like this:

• Это сандалии = These are sandals
• в которых удобно ходить весь день = that are comfortable to walk in all day
• даже если ты не любишь каблуки = even if you don’t like heels

So the full grammar is:

1. a main clause: Это сандалии
2. a relative clause with которых
3. a conditional/concessive idea with даже если

This kind of layered sentence is very common in natural Russian descriptions.