Я аккуратно положил книгу в сумку.

Положил is the past tense, masculine singular form of the verb положить.

• положить = to put / to place
• положил = put / placed (said by a male speaker)

Russian past tense often shows gender in the singular:

• положил = a man said it
• положила = a woman said it
• положило = neuter
• положили = plural

So Я аккуратно положил книгу в сумку would normally be said by a male speaker.

Because книгу is the accusative singular form of книга.

Here, книга is the direct object of the verb положил: it is the thing being put somewhere.

• nominative: книга = book
• accusative: книгу = book as the object of the action

For many feminine nouns ending in -а, the accusative singular changes to -у:

• книга → книгу
• сумка → сумку
• ручка → ручку

So положил книгу means put the book.

Because в сумку shows motion into the bag, and after в, that usually requires the accusative case.

Compare:

• в сумку = into the bag → direction, movement
• в сумке = in the bag → location, no movement

So:

• Я положил книгу в сумку. = I put the book into the bag
• Книга в сумке. = The book is in the bag

This is a very common Russian pattern:

• в + accusative = into
• в + prepositional = in

Here аккуратно means something like carefully, neatly, or tidily.

In this sentence, it describes how the action was done:

• Я положил книгу = I put the book
• Я аккуратно положил книгу = I carefully / neatly put the book

A useful thing to know is that аккуратно can sometimes mean slightly different things depending on context:

• carefully
• neatly
• tidily

So the exact English translation may vary a little.

Yes, it can sometimes be omitted, but in this sentence Я helps make the subject clear.

Russian often leaves out pronouns when the subject is obvious, but with the past tense, the verb does not show person clearly the way present-tense verbs do.

For example:

• положил tells you masculine singular
• but it does not by itself clearly tell you I vs. he

So:

• Я положил книгу в сумку. = clearly I put the book into the bag
• Положил книгу в сумку. = could mean I put the book into the bag if context makes it clear

Including Я makes the sentence more explicit.

Положил is perfective, and that fits because the sentence describes one completed action: the book was put into the bag.

Russian often uses:

• imperfective for process, repetition, or ongoing action
• perfective for a completed result

Here the focus is on the result: the book ended up in the bag.

The imperfective equivalent would be from класть:

• Я клал книгу в сумку.

But that sounds different. It suggests something like:

• I was putting the book into the bag
• I used to put the book into the bag
• I was engaged in that action

For a simple completed event, положил is the natural choice.

Russian положить is a common everyday verb meaning to put, to place, or to lay, depending on context.

In English, the best translation depends on style:

• I put the book into the bag = most natural everyday English
• I placed the book into the bag = more formal
• I laid the book into the bag = less natural here

So положил does not force one exact English word. It simply means that the speaker put/placed something somewhere.

No, Russian word order is fairly flexible, though some orders sound more neutral than others.

The sentence

• Я аккуратно положил книгу в сумку.

is a natural, neutral way to say it.

You may also hear:

• Я положил книгу в сумку аккуратно.
• Книгу я аккуратно положил в сумку.
• В сумку я аккуратно положил книгу.

These versions can shift the focus or emphasis.

Very roughly:

• the original sentence is neutral
• moving книгу forward can emphasize the book
• moving в сумку forward can emphasize where it was put

So Russian word order is not random, but it is more flexible than English.

Because сумка is a feminine noun ending in -а, and after в showing motion, it changes to the accusative singular сумку.

• nominative: сумка = bag
• accusative: сумку = into the bag

So in this sentence, both книгу and сумку are accusative, but for different reasons:

• книгу = direct object
• в сумку = destination after a verb of motion/placement

This is a very common thing in Russian: the same case can be used for different grammatical functions.

The main word stresses are:

• Я
• аккурАтно
• положИл
• кнИгу
• в сУмку

A simple pronunciation guide:

• аккурАтно ≈ ah-koo-RAHT-nuh
• положИл ≈ puh-lah-ZHEEL
• кнИгу ≈ KNEE-goo
• сУмку ≈ SOOM-koo

A natural rhythm would be something like:

Я аккурАтно положИл кнИгу в сУмку.

As always in Russian, correct stress matters a lot for sounding natural.