Я взял книгу оттуда, где ты её оставил.

They do slightly different jobs.

• оттуда = from there
• где ты её оставил = where you left it

So the structure is:

• Я взял книгу оттуда = I took the book from there
• где ты её оставил = where you left it

Together: I took the book from the place where you left it.

Russian often uses this kind of pair:

• там, где = there, where
• туда, куда = to the place where
• оттуда, откуда = from the place where/from where

Here, оттуда, где is natural because где ты её оставил describes the place itself. In everyday Russian, this is very common.

Because книга is the direct object of взял.

The verb взять means to take, and the thing being taken goes in the accusative:

• Я взял книгу = I took the book

Since книга is a feminine noun, its accusative singular form is:

• nominative: книга
• accusative: книгу

So книгу tells you that the book is the thing affected by the action.

Because её is also a direct object — this time of the verb оставил.

In где ты её оставил:

• ты = you
• оставил = left
• её = it/her

Here её refers back to книгу, so it means it:

• где ты её оставил = where you left it

So both книгу and её are accusative, but each belongs to a different verb:

• взял книгу
• оставил её

It can sometimes be omitted in informal speech, but in this sentence keeping её is the most normal and clear option.

• Я взял книгу оттуда, где ты её оставил. = fully natural
• Я взял книгу оттуда, где ты оставил. = not normal

Russian usually does not omit direct objects as freely as English sometimes can. In English, where you left it must have it, and Russian works similarly here.

So for a learner, the safe rule is: keep её.

This is about verbal aspect.

• взять = perfective
• брать = imperfective

взял presents the action as a completed whole: I took it.

That fits this sentence, because the speaker is talking about one completed action:

• the book was in a place
• the speaker took it from that place

If you said брал, it would sound more like:

• a repeated action,
• a process,
• or a context where completion is not the point.

So Я взял книгу... is the natural choice for I took the book... as a completed event.

For the same reason: aspect.

• оставить = perfective
• оставлять = imperfective

оставил means left as a completed action: you put it somewhere and it ended up there.

In this sentence, the place is defined by that completed action:

• where you left it

Using оставлял would suggest a repeated or ongoing action, which does not fit as well here.

So:

• где ты её оставил = where you left it
• natural, specific, completed event

Russian past tense is usually formed from the verb stem plus an -л ending.

Here:

• взять → взял
• оставить → оставил

For masculine singular subjects, the past tense often ends in a consonant + л:

• я взял = I took
• ты оставил = you left if speaking to a man

If the speaker or the person addressed were female, the forms would change:

• Я взяла книгу...
• где ты её оставила

Russian past tense agrees with gender and number, not person.

Because где ты её оставил is a subordinate clause.

Main clause:

• Я взял книгу оттуда

Subordinate clause:

• где ты её оставил

Russian normally puts a comma before subordinate clauses, just like English often does before where, that, when, because, etc.

So the comma marks the boundary between:

• the main statement
• the clause that describes the place

Yes. Russian word order is flexible, although each version gives a slightly different emphasis.

Neutral order:

• Я взял книгу оттуда, где ты её оставил.

Other possible orders:

• Я оттуда взял книгу, где ты её оставил. — possible, but less natural here
• Книгу я взял оттуда, где ты её оставил. — emphasizes the book
• Оттуда, где ты её оставил, я взял книгу. — emphasizes from that place

Russian often moves words for focus or contrast, but the basic sentence you were given is the most straightforward and natural.

Both are possible in some contexts, but they are not identical.

• оставить = to leave
• положить = to put/place down

So:

• где ты её оставил focuses on the result: that is the place where it remained
• где ты её положил focuses more on the act of placing it there

If the meaning is simply the place where you left the book, оставил is very natural. If you specifically mean the place where you put it down, then положил could also work.

Yes, a close alternative is:

• Я взял книгу оттуда, откуда ты её оставил.

But this version is less natural because оставить does not strongly suggest movement from a place. The combination откуда оставил sounds a bit awkward.

A more natural use of откуда would be with a verb involving removal or movement:

• Я взял книгу оттуда, откуда ты её достал.
• Я забрал книгу оттуда, откуда ты её принёс.

In your sentence, оттуда, где ты её оставил is the best everyday phrasing.

Sometimes, yes, because the verb form and context can make the subject clear.

For example:

• Взял книгу оттуда, где ты её оставил.
• Я взял книгу оттуда, где её оставил.

But in practice, Russian usually keeps the pronoun when it helps clarity or natural flow. In this sentence, using both я and ты is completely normal and clear.

So:

• omission is possible in some contexts
• keeping the pronouns is the safest and most natural choice for learners

Grammatically, её can mean either her or it, depending on what it refers to.

Here it refers to книгу, which is a feminine noun:

• книга = book

Because Russian nouns have grammatical gender, a feminine noun is replaced by её in the accusative/genitive form.

So in this sentence:

• её = it not her

This is very common in Russian:

• Я вижу машину. Я её купил. = I see the car. I bought it.

Even though машина is feminine, English still says it.