In maart begint de lente.

Because Dutch is a verb-second language in main clauses.

If the sentence starts with a time expression like In maart, the finite verb usually comes next:

• In maart begint de lente.

So the structure is:

• In maart = time expression
• begint = finite verb
• de lente = subject

If you put the subject first, you get:

• De lente begint in maart.

Both are correct. The version with In maart first puts a bit more focus on when it happens.

Yes, absolutely.

Both sentences are correct:

• In maart begint de lente.
• De lente begint in maart.

The difference is mainly word order and emphasis:

• In maart begint de lente. → emphasis on in March
• De lente begint in maart. → more neutral, subject-first order

In Dutch, in is normally used with months:

• in maart
• in april
• in december

Compare that with:

• op maandag = on Monday
• op 3 maart = on March 3rd

So a simple rule is:

• months → in
• days and dates → op

Because in Dutch, months are normally written with a lowercase letter.

So:

• maart
• april
• januari

This is different from English, where March is capitalized.

The same is true for seasons in Dutch:

• de lente
• de zomer
• de herfst
• de winter

They are only capitalized if they come at the beginning of a sentence.

Because lente is a noun, and in this kind of general statement Dutch normally uses the definite article:

• de lente = the spring

This is very natural in Dutch:

• De lente begint in maart.
• De zomer is warm.

You may sometimes see a noun without an article in other kinds of expressions, but here de lente is the normal standard form.

Begint is the present tense, third-person singular form of the verb beginnen (to begin).

Conjugation:

• ik begin = I begin
• jij begint = you begin
• hij/zij/het begint = he/she/it begins

Here the subject is de lente, which is singular, so Dutch uses:

• de lente begint

Because in the present tense, Dutch usually adds -t to the verb for third-person singular.

From beginnen, the stem is begin:

• ik begin
• de lente begint

So:

• stem = begin
• third-person singular = begin + t → begint

This is a very common Dutch pattern.

Yes.

In English, the subject usually comes before the verb, but Dutch is more flexible because of verb-second word order.

In:

• In maart begint de lente.

the subject is still de lente, even though it comes after begint.

A good clue is meaning: the spring is the thing that begins, so it is the subject.

A rough pronunciation guide is:

• In maart begint de lente.
• approximately: in maart bu-KHINT duh LEN-tuh

A few notes:

• g in begint is the Dutch throaty g/ch sound
• aa in maart is a long vowel
• final -e in de and lente is usually a soft uh sound

If you want a more IPA-style version, it is roughly:

• /ɪn maːrt bəˈɣɪnt də ˈlɛntə/

No, but it is the most straightforward and natural choice.

You might also hear:

• In maart start de lente.

But beginnen is usually the more basic and common verb for learners.

So:

• De lente begint in maart. = very standard
• De lente start in maart. = possible, but a bit less basic

Yes, all four seasons normally take de:

• de lente = spring
• de zomer = summer
• de herfst = autumn/fall
• de winter = winter

So you can make similar sentences:

• In juni begint de zomer.
• In september begint de herfst.

This is useful because learners often want to know whether a noun takes de or het. Here, lente is a de-word.