Efter leken hade barnet ett litet sår på knät som började blöda.

Because leken means the game / the play, while lek means play / game in a more general sense.

In Swedish, efter often takes a noun in the definite form when you mean a specific event:

• efter leken = after the game / after the playtime
• efter middagen = after dinner
• efter filmen = after the film

So efter leken refers to a particular play session or game that has just happened.

Barnet is the definite form of barn.

• ett barn = a child
• barnet = the child

Since the sentence is talking about a specific child, Swedish uses the definite form barnet.

Also note that barn is a neuter noun (ett noun), so the definite singular ending is -et:

• ett barn
• barnet

Because sår is an ett-word in Swedish:

• ett sår = a wound
• not en sår

Adjectives must agree with the noun. For an ett-word, the adjective usually gets -t in the singular indefinite form:

• en liten bil = a small car
• ett litet sår = a small wound

So:

• liten is used with en-words
• litet is used with ett-words

Both forms can exist in Swedish depending on the noun and style, but for knä, the standard definite singular form is knät:

• ett knä = a knee
• knät = the knee

So på knät means on the knee.

Swedish often uses the definite form for body parts where English might use a possessive:

• Han tvättade händerna = He washed his hands
• Hon slog sig i huvudet = She hit her head
• ett sår på knät = a wound on the knee

In context, it is naturally understood as the child’s knee.

Because Swedish often prefers the definite form of body parts instead of a possessive, especially when it is obvious whose body part is meant.

So Swedish commonly says:

• Han bröt armen = He broke his arm
• Hon hade ont i ryggen = She had pain in her back
• Barnet hade ett sår på knät = The child had a wound on the knee

Using sitt knä is possible in some contexts, but here it sounds less natural because the owner is already clear.

This is a relative clause. It describes sår:

• ett litet sår = a small wound
• som började blöda = that started to bleed

So the full noun phrase is:

• ett litet sår på knät som började blöda
• a small wound on the knee that started to bleed

Here, som means that / which.

It refers to sår.

The most natural reading is:

• the child had a small wound
• that wound started to bleed

Even though knät comes right before som, meaning and logic make it clear that the wound started bleeding, not the knee itself.

This kind of structure is common in Swedish and English alike.

Both are possible, but they mean slightly different things.

• började blöda = started to bleed
• blödde = was bleeding / bled

började blöda focuses on the beginning of the bleeding. It tells you that the wound was not bleeding before, and then it started.

If the sentence said ett litet sår på knät som blödde, that would mean a small wound on the knee that was bleeding. That describes the state, not the start of it.

Because the sentence begins with an adverbial phrase: Efter leken.

In Swedish main clauses, when something other than the subject comes first, the finite verb usually comes second. This is the V2 rule.

Normal order:

• Barnet hade ett litet sår på knät.
• The child had a small wound on the knee.

With Efter leken moved to the front:

• Efter leken hade barnet ett litet sår på knät.

So:

1. Efter leken = first position
2. hade = second position
3. barnet = after the verb

This is a very important Swedish word order pattern.

Hade is the past tense of ha (to have).

• ha = to have
• har = has / have
• hade = had

It is used because the sentence describes a past situation:

• After the game, the child had a small wound on the knee.

The verb började is also in the past tense:

• började = started

So the whole sentence is narrating past events.

It depends on context.

Lek can mean:

• play
• playing
• playtime
• a game, in some contexts

So efter leken could mean:

• after playtime
• after the game
• after the play session

If the sentence is about children playing generally, after playtime may sound more natural in English. If it was a specific game, after the game works well.

There actually is a definite marker, but in Swedish it is attached to the noun instead of being a separate word.

Compare:

• English: the game
• Swedish: leken

The ending -en is the definite article here.

So Swedish often expresses the by adding an ending:

• en lek = a game
• leken = the game

Yes, and that can be confusing at first.

For sår:

• ett sår = a wound
• flera sår = several wounds

The singular indefinite and plural indefinite forms look the same: sår.

You tell the difference from the article or the context:

• ett sår = singular
• många sår = plural

In this sentence, ett litet sår clearly shows that it is singular.

A useful breakdown is:

• Efter leken = time expression
• hade = finite verb
• barnet = subject
• ett litet sår på knät = object / thing the child had
• som började blöda = relative clause describing sår

So the pattern is roughly:

Time phrase + verb + subject + object + relative clause

This is a very typical Swedish sentence structure, especially because of the V2 rule after a fronted time phrase.