На лужайке дети играют в мяч, а один воробей прыгает рядом с ними.

На лужайке means on the lawn / in the grassy clearing.

• лужайка is the dictionary form.
• After на when talking about location, Russian usually uses the prepositional case.
• So:
  • лужайка → nominative
  • на лужайке → prepositional

Compare:

• На лужайке играют дети. = The children are playing on the lawn.
• На лужайку вышли дети. = The children came out onto the lawn.

So the difference is:

• where? → на лужайке
• to where? → на лужайку

Дети is the normal plural word for children.

Russian is irregular here:

• ребёнок = child
• дети = children

So дети is not formed regularly from ребёнок. You simply have to learn it as the plural form.

A few useful related words:

• ребёнок = child
• дети = children
• ребята = kids / guys / children, often more conversational

In this sentence, дети is the neutral and natural choice.

Because дети is plural.

Russian present-tense verbs must agree with the subject:

• он / она / оно играет = he/she/it plays
• они играют = they play

Since дети = children, the verb must be plural:

• дети играют

Later in the sentence, the subject changes:

• один воробей = one sparrow

That is singular, so the verb is singular:

• воробей прыгает

So the sentence has:

• дети играют = the children are playing
• воробей прыгает = a sparrow is hopping

In Russian, играть в + accusative is the normal pattern for playing a game or playing something like ball.

So:

• играть в мяч = to play ball
• играть в футбол = to play football/soccer
• играть в шахматы = to play chess

Here мяч is in the accusative case, but for this masculine inanimate noun, the accusative looks the same as the nominative:

• мяч = ball
• в мяч = ball, in the accusative after в

This is a set expression. English speakers often expect something like with a ball, but Russian commonly says играть в мяч.

Yes, but it means something a little different.

• играть в мяч = play ball, play a ball game
• играть с мячом = play with a ball

The first sounds more like the children are engaged in a ball game.
The second emphasizes the ball as an object they are using.

In this sentence, играют в мяч is the most natural choice.

А often means and, but with a slight sense of contrast or switch of focus.

So:

• и = and, simple addition
• а = and / while / whereas, with a contrast or change of topic
• но = but

In this sentence:

• На лужайке дети играют в мяч, а один воробей прыгает рядом с ними.

The second part adds another scene element, but it also shifts attention:

• the children are playing
• while / and meanwhile a sparrow is hopping nearby

So а is very natural here.

Один here can mean a literal one, but it can also sound like one particular sparrow or a single sparrow.

So один воробей suggests:

• there is just one sparrow
• it stands out from the rest of the scene

Without один, the sentence would still be grammatical:

• ...а воробей прыгает рядом с ними.

But один воробей gives a slightly more vivid picture, as if noticing one sparrow near the children.

Воробей means sparrow.

In this sentence it is the subject, so it is in the nominative singular:

• воробей прыгает = the sparrow hops / is hopping

It is a masculine noun, but it does not end in a hard consonant like many masculine nouns do. Its dictionary form ends in -ей:

• воробей

That is just part of the noun’s normal form. It is not a special case ending here.

It can mean both, depending on context.

Russian present tense often covers both:

• he jumps
• he is jumping

So:

• воробей прыгает can mean
  • the sparrow jumps
  • the sparrow is hopping/jumping

In a scene-description sentence like this one, English often prefers the continuous form:

• a sparrow is hopping nearby

Russian does not need a separate continuous tense for that.

Because рядом normally combines with с + instrumental.

So the pattern is:

• рядом с кем? с чем? = next to whom? next to what?

Examples:

• рядом с домом = next to the house
• рядом с мамой = next to mom
• рядом с ними = next to them

This is just the standard construction you need to learn with рядом.

After many prepositions, Russian personal pronouns add an initial н.

So:

• они = they
• ими = by them / with them
• с ними = with them / next to them

This extra н appears after prepositions in forms like:

• у него = at his place / he has
• к ней = to her
• с ними = with them
• рядом с ним = next to him

So с ими is not correct here; it must be с ними.

Ними is the instrumental plural form of они.

That happens because of the phrase:

• рядом с
  • instrumental

So:

• они = they
• с ними = with them / next to them

If you change the preposition, the pronoun changes too:

• рядом с ними = next to them
• около них = near them
• к ним = to them

So the form depends on what grammar comes before it.

Russian word order is fairly flexible, but changing it changes the focus or style.

The given sentence is very natural:

• На лужайке дети играют в мяч, а один воробей прыгает рядом с ними.

It starts by setting the scene:

• На лужайке = on the lawn

Then it tells you who is there and what is happening.

Other orders are possible, for example:

• Дети играют в мяч на лужайке...
• Рядом с ними прыгает один воробей...

These are grammatical, but they highlight different parts of the sentence.

So the original word order is not the only possible one, but it is a very normal descriptive order.

Yes. Both verbs here are imperfective:

• играть = to play
• прыгать = to jump / hop

That matters because the sentence is describing an ongoing scene, not a single completed action.

Imperfective verbs are commonly used for:

• actions in progress
• repeated actions
• general description

That fits this sentence perfectly:

• the children are playing
• the sparrow is hopping

If you used perfective verbs here, the meaning would change toward a completed or one-time action, which would not fit this calm scene description as well.

Not exactly.

• лужайка = a little lawn, grassy patch, grassy clearing
• газон = lawn, especially a maintained lawn or grass area

Лужайка often feels a bit more natural, outdoorsy, or picturesque.
Газон can sound more like a formal lawn, such as in a park or in front of a building.

So in a sentence with children and a sparrow, лужайка creates a nice natural image.

A fairly literal breakdown would be:

• На лужайке = On the lawn
• дети = children
• играют в мяч = play ball
• а = while / and
• один воробей = one sparrow
• прыгает = hops / is hopping
• рядом с ними = next to them / nearby them

So a very literal version would be:

On the lawn, children are playing ball, and one sparrow is hopping next to them.

That helps show how the Russian sentence is built, even if a smoother English translation might phrase it a little differently.