Depois do jogo, ela colocou gelo no joelho.

Because do is the contraction of de + o.

• de = of / from / after in different contexts
• o jogo = the game
• de + o jogo → do jogo

So depois do jogo literally comes from depois de o jogo, but Portuguese normally contracts it to depois do jogo.

Similar contractions:

• de + a = da
• de + os = dos
• de + as = das

It is a time expression meaning after the game.

• depois = after / later
• depois de is the full pattern
• before a noun with an article, de often contracts:
  • depois do jogo
  • depois da aula
  • depois dos treinos

So the structure is:

depois de + noun
or, with contraction,
depois do/da/dos/das + noun

Colocou is the preterite form of colocar.

Here it means she put or she placed in the sense of a completed action in the past.

Conjugation of colocar in the preterite:

• eu coloquei
• você/ele/ela colocou
• nós colocamos
• vocês/eles/elas colocaram

In this sentence, ela colocou = she put.

Because colocou describes a single completed action.

• ela colocou gelo no joelho = she put ice on her knee
• ela colocava gelo no joelho would suggest something habitual, repeated, or ongoing in the past, like she used to put ice on her knee or she was putting ice on her knee, depending on context

So colocou is the natural choice for one specific event after the game.

In Portuguese, substances and materials often appear without an article when speaking in a general sense.

So:

• colocou gelo no joelho = she put ice on her knee

This sounds natural because gelo is being treated as a substance, not as a specific previously mentioned set of ice cubes.

If you say colocou o gelo, that sounds more like she put the ice, referring to specific ice already known in the conversation.

Because no is the contraction of em + o.

• em can mean in / on / at, depending on context
• o joelho = the knee
• em + o → no

So:

• no joelho = on the knee

Other common contractions:

• em + a = na
• em + os = nos
• em + as = nas

Portuguese often uses a definite article with body parts when the owner is clear from the context.

So instead of saying the equivalent of her knee, Portuguese often says:

• no joelho = literally on the knee

Because the subject is ela, listeners naturally understand it is her knee.

You can say no joelho dela if you need to be explicit, especially to avoid ambiguity:

• ela colocou gelo no joelho dela

But in many everyday sentences, just no joelho is more natural.

Not always. Portuguese often allows the subject pronoun to be omitted when the context makes it clear.

So you could say:

• Depois do jogo, colocou gelo no joelho.

That can still mean After the game, she put ice on her knee, if the context already tells us who we are talking about.

However, ela may be included:

• for clarity
• for emphasis
• when the speaker wants to contrast her with someone else

Because Depois do jogo is an introductory time phrase.

The comma helps separate that opening phrase from the main clause:

• Depois do jogo, ela colocou gelo no joelho.

In writing, this is very common and natural. In informal writing, some people may omit the comma, but using it is a good standard choice.

Yes. Portuguese em is broader than English in.

Depending on context, em can correspond to:

• in
• on
• at

So:

• no joelho is naturally translated as on the knee
• not necessarily in the knee

The exact English preposition depends on what sounds natural in English for that situation.

Yes. Pôs is the preterite of pôr, and it also means put.

So these are both possible:

• ela colocou gelo no joelho
• ela pôs gelo no joelho

Colocou may feel slightly more neutral or transparent for learners because it comes from colocar.
Pôs is very common too, but pôr is a more irregular verb.

In Brazilian Portuguese, joelho is roughly pronounced zho-EL-yoo.

A few points:

• j sounds like the s in measure or the zh sound
• lh is a special Portuguese sound, similar to the lli in million for many English speakers, though not exactly the same
• the stress falls on e: jo-EL-ho

A rough learner-friendly approximation:

• zho-EL-yoo

A rough Brazilian Portuguese approximation:

• jogo ≈ ZHO-goo
• gelo ≈ ZHE-loo
• joelho ≈ zho-EL-yoo

Notes:

• initial j in Portuguese sounds like zh
• unstressed final o often sounds like oo in Brazilian Portuguese
• ge in gelo also has the zh sound

So all three words begin with that soft zh sound, not an English j sound.

The sentence follows a very common Portuguese pattern:

subject + verb + object + location

• ela = subject
• colocou = verb
• gelo = object
• no joelho = location / target

So:

• ela colocou gelo no joelho

This is a very natural and standard word order in Portuguese.

Yes, often.

• Depois do jogo = After the game
• Após o jogo = After the game

Both are correct.
In everyday speech, depois de is very common and often feels more conversational.
Após can sound a little more formal or written, depending on context.