Learn Hardcore Japanese: watasitati no musuko ha supootu ga daisuki de, houkago ni tomodati to sakkaa wo simasu. - Our son loves sports and plays soccer with his friends after school.

So は is not “subject” in a strict grammatical sense; it’s “topic.” The grammatical subject inside the clause with 好き is actually スポーツ (marked by が).

Why is it スポーツが大好き, not スポーツを大好き?

With 好き and 大好き, Japanese uses the pattern:

X は Y が好き / 大好き
(As for X, Y is liked / loved)

So in this sentence:

私たちの息子は = as for our son (topic)
スポーツが大好き = sports are (what he) really loves

が marks the thing that is liked/loved:

私は日本語が好きです。 = I like Japanese.
母は犬が大好きです。 = My mother loves dogs.

Using を here would be unnatural; を is normally for direct objects of actions (eat, drink, make, do, etc.), not for 好き.

What’s the difference between 好き and 大好き?

Both are na‑adjectives (they work like adjectives, but grammatically are a type of noun).

好き = like / fond of
大好き = really like / love (very strong like)

Examples:

私はコーヒーが好きです。 = I like coffee.
私はコーヒーが大好きです。 = I love coffee / I really like coffee.

In this sentence, スポーツが大好き expresses a strong liking:
> Our son really loves sports.

What is the で at the end of 大好きで doing? Why isn’t it just 大好き。放課後に…?

大好きで is the て‑form (continuative form) of the na‑adjective 大好き.

大好きだ → 大好きで (linking form)

This て‑form links two clauses, like “and” or “and so”:

スポーツが大好きで、放課後に友達とサッカーをします。
= He really loves sports and (so) he plays soccer with his friends after school.

You could say:

スポーツが大好きです。放課後に友達とサッカーをします。

That would be two separate sentences. Using 大好きで makes it flow as one connected idea, showing that these facts are related.

Why is there に after 放課後: 放課後に?

に is used here as a time marker: “at / on / in (time).”

放課後 = after school
放課後に = at/after school time, after school

General pattern:

３時に行きます。 = I’ll go at 3 o’clock.
日曜日に友達に会います。 = I meet my friends on Sunday.

So 放課後に友達とサッカーをします =
> (He) plays soccer with his friends after school.

What does 友達と mean? What is the role of と here?

と has several uses; here it means “with” (companion).

友達 = friend / friends
友達と = with (his) friends

Examples:

家族と旅行します。 = I travel with my family.
先生と話します。 = I talk with the teacher.

So 友達とサッカーをします =
> (He) plays soccer with (his) friends.

Why is it サッカーをします for “play soccer”? Why use する and を?

In Japanese, many activities are expressed as:

[activity noun] をする = do [activity] / play [sport]

Here:

サッカー = soccer
サッカーをする = to play soccer

Other examples:

テニスをします。 = (I) play tennis.
ゲームをします。 = (I) play games.
勉強をします。 = (I) study.

So サッカーをします literally is “do soccer,” but in English we say “play soccer.”
を marks the activity noun as the object of する.

Why is “he” not written anywhere in Japanese? How do we know it’s he?

Japanese often omits the subject when it’s clear from context.

We already established the topic at the beginning:

私たちの息子は = as for our son

After that, Japanese doesn’t need to keep repeating 息子 or use a pronoun like “he.” The listener assumes the same topic continues until something clearly changes it.

So:

私たちの息子はスポーツが大好きで、放課後に友達とサッカーをします。
Literally:
> As for our son, (sports are what he) really loves, and (after school he) plays soccer with (his) friends.

The “he” is understood from 息子 + context.

Could the word order be changed, like putting 放課後に earlier? How flexible is Japanese word order here?

Japanese word order is relatively flexible as long as the particles stay attached to the correct words, and the verb usually comes last.

You could say, for example:

私たちの息子は放課後に友達とサッカーをします。
私たちの息子は放課後にスポーツが大好きで、友達とサッカーをします。 (less natural)

But the basic natural ordering is:

Topic: 私たちの息子は
First statement about the topic: スポーツが大好きで
Additional information: 放課後に友達とサッカーをします。

Reordering too much can sound awkward or change the focus, but time phrases (放課後に) and location phrases often move around quite freely before the verb.

What is the politeness level of します in サッカーをします? Is this formal?

Yes. します is the polite form of する.

する = plain (casual)
します = polite

So:

サッカーをする。 = I/he play(s) soccer. (casual)
サッカーをします。 = I/he play(s) soccer. (polite)

Because the sentence uses します, it’s in the polite style, appropriate for talking to people you’re not close to, or generally in neutral/pleasant conversation.

Why is it 息子, not 息子さん here? Would 息子さん be wrong?

息子 by itself means my/our son when you’re talking about your own family.

Talking about your own son: 息子 (no さん)
Talking about someone else’s son: often 息子さん or their name + さん

So:

私たちの息子はスポーツが大好きです。
= Our son loves sports. (normal, humble about your own family)

Using 息子さん for your own son can sound a bit strange or overly polite/self‑important. It’s mainly used when referring respectfully to another person’s son.

What does 放課後 literally mean?

放課後 is made of:

放 (release)
課 (lesson, class)
後 (after)

So literally: “after releasing (ending) classes” → after school (time).

In everyday use, 放課後 simply means after school, i.e., the time after regular classes finish.