Я не знаю вік своєї подруги, але вона виглядає дуже молодо.

Ukrainian often uses the reflexive possessive свій when the possessor is the same as the subject of the clause.

Here, the subject is я, so своєї подруги means of my friend. This is usually more natural than моєї подруги in this kind of sentence.

So:

• я ... своєї подруги = I ... my own friend
• він ... своєї подруги = he ... his own friend

Using моєї is not impossible, but своєї is the normal choice here.

Because свій has to match подруги in gender, number, and case.

Here, подруги is:

• feminine
• singular
• genitive

So the matching form of свій is своєї.

That is why you get своєї подруги.

Because Ukrainian expresses the age of my friend with a noun + genitive structure.

So:

• вік = age
• подруги = of the friend

This is the same basic idea as English the age of my friend, except Ukrainian uses case endings instead of the word of.

In this sentence, вік is the direct object of знаю, so the accusative is used. For an inanimate masculine noun like вік, the accusative looks the same as the nominative: вік.

A learner may also come across не знаю віку своєї подруги. That genitive form can appear after negation in Ukrainian, and it is also possible. But не знаю вік is fully correct and natural in modern usage.

Here виглядає means looks in the sense of appears or seems by appearance.

So вона виглядає дуже молодо means that she appears young when you see her. It does not necessarily mean she actually is young.

After виглядати, Ukrainian very often uses an adverb to describe appearance:

• виглядати молодо = to look young
• виглядати добре = to look good
• виглядати дивно = to look strange

By contrast, молода is an adjective and is more natural in sentences like:

• Вона молода. = She is young.

So:

• вона молода = she is young
• вона виглядає молодо = she looks young

Usually подруга means female friend.

In some contexts it can be understood as girlfriend, but that is less automatic than in English. If someone clearly means a romantic partner, Ukrainian often uses words like дівчина, кохана, or simply makes it clear from context.

So in this sentence, подруга will normally be understood as female friend.

Yes, it can often be omitted, because Ukrainian does not always need an explicit subject pronoun.

But вона is perfectly natural here. It helps make the contrast clearer:

• Я не знаю вік своєї подруги, але вона виглядає дуже молодо.

The pronoun makes the second clause feel complete and slightly more explicit. Without it, the sentence can still work in the right context, but this version is very normal.

No. Ukrainian word order is fairly flexible.

This sentence uses a neutral, natural order:

• Я не знаю вік своєї подруги, але вона виглядає дуже молодо.

You can change the order for emphasis, but the meaning stays basically the same if the case endings make the roles clear. For example, a different order might sound more emphatic or more literary, while the given version is a good standard pattern for learners.

Because але means but and introduces a new clause.

In Ukrainian, coordinating conjunctions like але commonly take a comma when they join two clauses:

• Я не знаю вік своєї подруги, але вона виглядає дуже молодо.

So the comma is standard punctuation here.