Я положил кусочек сыра на хлеб.

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

So this tells you:

• the action happened in the past
• the subject is singular
• the speaker is grammatically masculine

Examples:

• Я положил — if a man is speaking
• Я положила — if a woman is speaking
• Они положили — they put

Also, положить is a perfective verb, so it presents the action as completed: I put / I placed.

Russian often uses a perfective verb when talking about a single completed action.

• положил = put / placed as a finished act
• клал = was putting / used to put / put repeatedly, depending on context

In this sentence, the speaker is talking about one finished action, so положил is the natural choice.

A useful verb pair to learn is:

• класть — imperfective
• положить — perfective

You may hear ложить in colloquial speech, but it is generally considered nonstandard in modern standard Russian, so learners should normally use класть / положить.

Because after a noun like кусочек meaning a little piece, Russian usually puts the thing being measured or divided into the genitive case.

So:

• кусочек сыра = a little piece of cheese
• кусок хлеба = a piece of bread
• чашка чая = a cup of tea
• бутылка воды = a bottle of water

This is a very common Russian pattern: piece/cup/bottle/etc. + genitive.

Кусочек means a little piece or a small bit. It is a diminutive form of кусок, which means piece / chunk.

So:

• кусок сыра = a piece of cheese
• кусочек сыра = a small piece / little piece of cheese

The diminutive can suggest:

• small size
• a slightly more natural or everyday tone
• sometimes a mild affectionate or softening nuance

In this sentence, кусочек сыра sounds very natural for food.

Because Russian uses two different cases after на, depending on the meaning:

• на + accusative = movement or placement onto something
• на + prepositional = location on something

Here the cheese is being placed onto the bread, so Russian uses на хлеб.

Compare:

• Я положил кусочек сыра на хлеб. — I put a piece of cheese onto the bread.
• Кусочек сыра лежит на хлебе. — The piece of cheese is lying on the bread.

So the sentence focuses on the action of putting, not the resulting location by itself.

Because хлеб is a masculine inanimate noun, and for nouns like this, the accusative singular is often identical to the nominative singular.

So:

• nominative: хлеб
• accusative: хлеб

There is still an accusative meaning here, but the form happens to look the same.

This is very common with masculine inanimate nouns:

• вижу стол
• положил нож на стол
• положил сыр на хлеб

It can be omitted in some contexts, but in this sentence я is very natural and often helpful.

In the past tense, положил tells you only that the subject is:

• singular
• masculine

It does not by itself tell you whether the subject is I, you, or he. So я is often used to make the subject clear.

Compare:

• Я положил кусочек сыра на хлеб. — clearly I put...
• Положил кусочек сыра на хлеб. — possible in context, but the subject must already be obvious

Yes. Russian word order is much more flexible than English word order.

The neutral order here is:

• Я положил кусочек сыра на хлеб.

But other orders are possible:

• Я положил на хлеб кусочек сыра.
• Кусочек сыра я положил на хлеб.
• На хлеб я положил кусочек сыра.

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

For example:

• На хлеб я положил кусочек сыра may emphasize onto the bread
• Кусочек сыра я положил на хлеб may emphasize the piece of cheese

Literally, хлеб means bread. It does not specifically mean slice.

But in context, especially with food, Russian often leaves that implicit. So на хлеб may naturally be understood as on the bread / on a piece of bread / on a slice of bread, depending on the situation.

If you want to say a slice of bread explicitly, you could say:

• ломтик хлеба — a slice of bread
• кусок хлеба — a piece of bread

So this sentence is natural Russian, even though English might sometimes prefer on a slice of bread.

The main stresses are:

• Я положИл кусОчек сЫра на хлЕб.

Word by word:

• положИл
• кусОчек
• сЫра
• хлЕб

Stress is very important in Russian because it is not always predictable, so it is best to learn each word together with its stress.