Le chant est un loisir formidable.

Because le is often used in French to talk about something in general.

So Le chant est un loisir formidable means something like Singing is a wonderful hobby/leisure activity in a general sense.

• Le chant = singing, as a general activity
• Un chant = a song/chant, or one instance of singing in some contexts

French uses the definite article more often than English for general statements:

• Le sport est important. = Sport is important.
• La musique est belle. = Music is beautiful.

Here, chant means singing.

It comes from the verb chanter (to sing), but here it is a noun, not a verb.

Depending on context, chant can also mean:

• song
• singing
• chant

But in this sentence, the natural meaning is singing as an activity.

It is masculine: le chant.

That is why the sentence uses:

• Le chant
• not La chant

This also affects any adjectives or articles used with it.

Est is the third-person singular form of the verb être (to be).

So:

• je suis = I am
• tu es = you are
• il/elle/on est = he/she/one is

Since Le chant is singular, French uses est:

• Le chant est... = Singing is...

Un loisir means a leisure activity, a pastime, or a hobby.

So Le chant est un loisir formidable means that singing is being described as a very enjoyable or excellent pastime.

A useful distinction:

• le loisir can refer to leisure in general
• un loisir usually means a specific hobby or leisure activity

Examples:

• La lecture est un loisir. = Reading is a hobby/pastime.
• J’ai plusieurs loisirs. = I have several hobbies.

Yes—this is a very useful vocabulary point.

In modern French, formidable usually means:

• great
• wonderful
• excellent
• terrific

So here it is clearly positive:

• un loisir formidable = a wonderful hobby

This is a false friend for English speakers, because English formidable often means intimidating, powerful, or impressive in a scary way. French formidable is usually much more positive.

It actually already agrees correctly with loisir, which is masculine singular.

The adjective formidable has the same written form in the masculine singular and feminine singular:

• un loisir formidable
• une activité formidable

But in the plural, it changes:

• des loisirs formidables
• des activités formidables

So the adjective is agreeing normally; it just happens to look the same in the singular masculine and feminine.

Because in French, many adjectives come after the noun.

So:

• un loisir formidable
• literally: a hobby wonderful
• naturally in English: a wonderful hobby

Some French adjectives come before the noun, but many—especially descriptive ones like formidable—come after it.

Yes, absolutely.

• Le chant est un loisir formidable = Singing is a wonderful hobby
• Chanter est un loisir formidable = To sing / Singing is a wonderful hobby

Both are grammatical, but there is a slight difference in feel:

• Le chant uses a noun and sounds a little more like talking about singing as an activity or art form
• Chanter uses the infinitive verb and focuses more directly on the act of singing

Both are very natural.

Because French normally needs an article before a countable singular noun like loisir.

So you say:

• C’est un loisir
• not C’est loisir

In this sentence, loisir is being used as a singular countable noun meaning a hobby / a pastime, so un is required.

A careful pronunciation is roughly:

Le chant est un loisir formidable
IPA: /lə ʃɑ̃ ɛ tœ̃ lwa.ziʁ fɔʁ.mi.dabl/

A few helpful pronunciation notes:

• chant has a nasal vowel: ʃɑ̃
• est un is often linked smoothly in speech
• loisir is pronounced roughly lwa-zeer
• formidable in French sounds more like for-mee-dabl, not exactly like the English word

A rough English-style approximation would be: luh shah(n) eh-tuh(n) lwah-zeer for-mee-dahbl

Yes, it is natural and correct.

It sounds like a straightforward statement describing singing as a hobby. Depending on context, native speakers might also say things like:

• Le chant est un loisir très agréable.
• Le chant est une activité formidable.
• Chanter est un excellent loisir.

But Le chant est un loisir formidable is perfectly good French.