Эта карта старая, но я всё ещё пользуюсь ею.

Because карта is a feminine noun, so the adjective has to agree with it.

• карта = feminine, singular
• nominative feminine adjective form of старый is старая

So:

• старая карта = an old map/card
• эта карта старая = this map/card is old

For the same reason: эта has to agree with карта in gender, number, and case.

• этот = masculine
• эта = feminine
• это = neuter
• эти = plural

Since карта is feminine singular, you need эта.

In Russian, the verb to be is normally omitted in the present tense.

So Russian says literally:

• Эта карта старая = This map/card old

but it means:

• This map/card is old

This is completely normal in Russian.

Всё ещё means still.

So:

• я всё ещё пользуюсь ею = I still use it

It emphasizes that the situation continues despite what was said before. In this sentence, the idea is:

• The map/card is old, but I still use it.

You will also see just ещё, but всё ещё is a very common way to say still.

Пользуюсь is the 1st person singular present tense of пользоваться.

• dictionary form: пользоваться
• я пользуюсь = I use

The -ся / -сь ending marks the verb as reflexive in form. Many Russian verbs are built this way, and you simply learn them as whole verbs.

In this case, the standard verb is пользоваться + instrumental case.

Because пользоваться takes the instrumental case, not the accusative.

That is the key grammar point.

• её = usually accusative/genitive her / it
• ею = instrumental by/with her, by/with it

So after пользоваться, Russian uses instrumental:

• пользоваться картой = to use a map/card
• пользоваться ею = to use it

An English speaker often expects a direct object here, but Russian treats this verb differently.

Yes. Ей and ею can both be instrumental singular feminine pronoun forms here.

So both are possible:

• я пользуюсь ей
• я пользуюсь ею

In modern everyday speech, ей is very common.
Ею can sound a bit more formal, literary, or emphatic.

So this sentence is correct, but ...пользуюсь ей would also be natural.

Because that is simply the verb’s required pattern, often called verb government.

In Russian, many verbs require a specific case, and it does not always match English logic.

For example:

• интересоваться чем? = to be interested in what? → instrumental
• гордиться чем? = to be proud of what? → instrumental
• пользоваться чем? = to use what? → instrumental

So you should learn пользоваться together with its case pattern:

• пользоваться + instrumental

Yes. Russian word order is flexible.

This sentence:

• Эта карта старая, но я всё ещё пользуюсь ею.

could also appear as:

• Эта карта старая, но я ещё пользуюсь ею.
• Эта карта старая, но ею я всё ещё пользуюсь.

The basic meaning stays the same, but the emphasis changes.

The given version sounds natural and neutral:

• first clause states the fact
• second clause emphasizes I still use it

Карта can mean either map or card, depending on context.

For example:

• географическая карта = map
• банковская карта = bank card
• игральная карта = playing card

So the grammar of the sentence does not change, but the exact meaning depends on the situation.

Because но means but, and in Russian it normally joins two clauses with a comma before it.

Here the two parts are:

• Эта карта старая
• я всё ещё пользуюсь ею

So the comma is standard:

• Эта карта старая, но я всё ещё пользуюсь ею.

Yes, here the correct form is всё, meaning everything in other contexts, but in the fixed phrase всё ещё it means still.

In many Russian texts, especially informal ones, ё is written as е, so you may see:

• все еще

But in this sentence, the meaning is still still, not all yet. The intended word is всё.