Оператор ответила вежливо и сказала, что товара пока нет в наличии.

Because the speaker is referring to a female operator.

The noun оператор has a masculine-looking form, but it can refer to either a man or a woman, depending on the real person. In the past tense, Russian verbs agree with the person's gender:

• ответил / сказал = he answered / he said
• ответила / сказала = she answered / she said

So Оператор ответила... tells you that the operator was a woman.

They are close, but not identical.

• ответила = answered / replied
• сказала = said

So the sentence structure is roughly:

• The operator replied politely and said that...

This is very natural in Russian. First, she replied, and then the content of her reply is introduced with сказала, что...

Вежливо is an adverb, meaning politely.

It comes from the adjective:

• вежливый = polite

And the adverb form is:

• вежливо = politely

So:

• ответила вежливо = answered politely

This is similar to English polite → politely, though in Russian the form is much simpler.

Что here means that and introduces a subordinate clause.

So:

• сказала, что товара пока нет в наличии = said that the item is not in stock yet / for now

This is one of the most common uses of что in Russian.

Compare:

• Он сказал, что придёт. = He said that he would come.
• Я знаю, что это правда. = I know that it is true.

Because after нет in Russian, the noun is usually in the genitive case.

Here:

• товар = nominative singular
• товара = genitive singular

So:

• товара нет = there is no product / the item is not available

This is a very important pattern:

• У меня нет времени. = I don’t have time.
• Здесь нет магазина. = There is no shop here.
• Товара нет. = The item is unavailable.

So нет strongly often triggers the genitive.

Because the sentence is talking about the item / the product in a general or context-specific singular sense.

Russian often uses singular where English might also use singular:

• товара нет в наличии = the item is not in stock

If the speaker wanted to talk about multiple products, then plural could appear:

• товаров нет в наличии = the products are not in stock

In your sentence, singular suggests one product or one type of item being discussed.

Here пока means for now, at the moment, or not yet depending on context.

So:

• товара пока нет в наличии = the item is not in stock yet / for now

It softens the statement a little and suggests the situation may change later.

Compare:

• Его пока нет. = He’s not here yet.
• Я пока не знаю. = I don’t know yet / for now I don’t know.

So пока often adds the idea of temporary absence.

В наличии is a fixed expression meaning:

• in stock
• available
• on hand

Yes, literally it comes from the idea of something being present, but in modern usage it is just a standard phrase for availability of goods.

So:

• нет в наличии = is not in stock
• есть в наличии = is in stock / available

Examples:

• Этот товар есть в наличии. = This item is in stock.
• Этого товара нет в наличии. = This item is not in stock.

It is best learned as a whole expression.

Because Russian has no articles like a/an/the.

So товар / товара can mean:

• a product
• the product
• the item

The exact meaning comes from context.

In this sentence, English would usually translate it as the item or the product, because both speaker and listener probably know which product they are talking about.

If Russian needs to be more specific, it can add words like:

• этот товар = this product
• нужный товар = the needed product
• товар, который вы заказали = the product you ordered

Yes, Russian word order is fairly flexible, but different orders change the focus or emphasis.

The version here:

• товара пока нет в наличии

sounds natural and neutral in this context.

Other possible versions:

• Пока товара нет в наличии.
• Товара нет пока в наличии.
• В наличии товара пока нет.

These all mean roughly the same thing, but they can sound slightly different in emphasis. Russian often uses word order to highlight what is new, important, or contrastive.

So the order in your sentence is simply a smooth, natural way to say it.

Yes. Both are perfective past forms:

• ответила from ответить
• сказала from сказать

Perfective verbs present the actions as completed single events:

• she replied
• she said

That fits the context well: the operator gave one reply and said one thing.

If you used imperfective forms, the meaning would change:

• отвечала = was answering / used to answer
• говорила = was speaking / used to say

So the perfective forms are the natural choice for a single finished interaction.