Le canard nage.

A common standard-French pronunciation is /lə ka.naʁ naʒ/.

A rough English-friendly guide:

• le → luh (with a very light vowel)
• canard → ka-nar
• nage → nahzh

A few important points:

• The r in canard is the French r, made at the back of the throat.
• The final d in canard is silent.
• In nage, the g before e sounds like the s in measure.

In French, a singular countable noun usually needs a determiner such as an article.

So French normally says:

• le canard = the duck
• un canard = a duck

Saying just canard nage would sound incomplete in standard French. English can sometimes omit articles in places where French cannot, but here French needs one.

Because canard is a masculine noun.

In French:

• le is used with singular masculine nouns
• la is used with singular feminine nouns

So:

• le canard = the duck

This is one of the things English speakers have to get used to: French nouns have grammatical gender, even when the object itself is not obviously male or female.

A good habit is to learn nouns together with their article:

• le canard, not just canard

Not necessarily in everyday use.

Canard is often used as the normal general word for duck. Depending on context, it can also refer to a male duck, but in simple beginner sentences like this, it is usually best understood as just duck.

If you specifically wanted a female duck, French also has cane.

Because nager is the infinitive, meaning to swim.

After a subject like le canard, French normally uses a conjugated verb:

• nager = to swim
• le canard nage = the duck swims / the duck is swimming

So nage is the correct form for this sentence.

Nage is the present tense, third person singular.

It is the form used with:

• il nage = he swims / he is swimming
• elle nage = she swims / she is swimming
• le canard nage = the duck swims / is swimming

So the noun le canard works like he/it in terms of verb agreement.

French often uses the simple present where English might use either:

• The duck swims
• The duck is swimming

So Le canard nage can mean either one, depending on context.

If French wants to strongly emphasize that the action is happening right now, it can say:

• Le canard est en train de nager = The duck is in the process of swimming / is swimming right now

But for a basic sentence, Le canard nage is completely normal.

Yes.

• In canard, the final d is silent.
• In nage, the final e is silent.

So although the words are spelled:

• canard
• nage

they are pronounced more like:

• ka-nar
• nahzh

Silent final letters are very common in French, so this is something worth getting used to early.

You would say:

Les canards nagent.

That means The ducks swim or The ducks are swimming.

Changes:

• le → les
• canard → canards
• nage → nagent

One important pronunciation note:

• The -ent ending in nagent is usually silent
• The s in canards is also usually silent

So the plural sentence is not pronounced very differently from the singular one.