Nadam se da će se moj gležanj brzo oporaviti.

Nadam se means I hope. The basic verb is nadati se, which is a reflexive verb in Croatian. That means the little word se is part of the verb and cannot normally be left out.

So:

• nadam = I hope would be incomplete/incorrect here
• nadam se = I hope

This se does not literally mean myself in normal English translation here. It is just part of how the verb works in Croatian.

Croatian often uses da to introduce a clause after verbs like hope, think, know, want, and similar verbs.

So:

• Nadam se da... = I hope that...

In English, that is often optional, but in Croatian da is very common and natural here.

English often says I hope my ankle will recover quickly without a separate marker like da. Croatian normally prefers a full clause here:

• Nadam se da će se moj gležanj brzo oporaviti.

Literally, this is something like:

• I hope that my ankle will recover quickly.

A bare infinitive after nadam se would not be the normal structure here.

Because there are two different verbs, and both use se:

1. nadam se = I hope
2. oporaviti se = to recover

So the first se belongs to nadati se, and the second se belongs to oporaviti se.

Even though they look identical, they are attached to different verbs:

• Nadam se ...
• ... će se oporaviti

Croatian future tense is often made with a form of htjeti (to want) plus the infinitive.

Here:

• će = will
• oporaviti = recover

So:

• će se oporaviti = will recover

The subject is moj gležanj, which is third person singular, so the auxiliary is će.

Because after će, Croatian uses the infinitive.

So:

• oporaviti = infinitive, to recover
• će se oporaviti = will recover

Also, oporaviti se is the perfective form, which fits well with a future result: the ankle recovering.

A related imperfective verb is oporavljati se, which suggests an ongoing process:

• Moj se gležanj oporavlja. = My ankle is recovering.

But in this sentence, the focus is on the hoped-for recovery as a whole, so oporaviti se is a natural choice.

Gležanj is in the nominative case because it is the subject of the clause da će se moj gležanj brzo oporaviti.

The thing doing the recovering is moj gležanj:

• moj = my
• gležanj = ankle

Since it is masculine singular nominative, the possessive adjective also matches:

• moj gležanj

Yes, Croatian can sometimes omit possessives when the owner is obvious, especially with body parts. So a Croatian speaker might also say something like:

• Nadam se da će mi se gležanj brzo oporaviti.

Here mi means to me / my, and it often sounds very natural with body parts.

But moj gležanj is still correct and clear. It simply states my ankle more explicitly.

Croatian word order is flexible, but small unstressed words called clitics tend to come early in the clause. Both će and se are clitics here.

So after da, it is very natural to get:

• da će se moj gležanj brzo oporaviti

That early placement of će se is normal Croatian syntax.

The adverb brzo can move around somewhat, but this position is very natural:

• ... moj gležanj brzo oporaviti

Yes, to some extent. Croatian allows some movement for emphasis or style.

For example:

• Nadam se da će se moj gležanj brzo oporaviti.
• Nadam se da će se moj gležanj oporaviti brzo.

The first version is more neutral and natural. Putting brzo before the infinitive is the most common choice here.

A rough guide:

• će sounds approximately like chyeh, but with a softer ć sound than English ch
• gležanj is roughly GLEH-zhany or GLEH-zhahnj, depending on how precisely you imitate Croatian sounds

A few important sound notes:

• ž sounds like the s in measure
• nj is like the ny in canyon
• ć is a soft Croatian consonant that English does not match perfectly

So gležanj has:

• gl
• e
• ž as in measure
• a
• nj as in canyon

Oporaviti se is a good general verb for recover and works well here.

Depending on context, Croatian might also use other verbs:

• zacijeliti = heal up (often for wounds, tissues, fractures healing)
• izliječiti se = recover/get cured more generally, often for illness
• sanirati se or similar expressions in medical contexts

But for a sentence like this, gležanj se brzo oporavi / će se oporaviti sounds natural and understandable.

Yes, but that would happen in a different sentence structure.

In a main clause, Croatian often writes the future like this:

• Moj će se gležanj brzo oporaviti.

You may also see forms like:

• Oporavit će se brzo.

But in your sentence, after da, the normal structure is:

• da će se ... oporaviti

So Nadam se da će se moj gležanj brzo oporaviti is exactly the kind of pattern learners should expect after nadam se da.