La póliza empieza en marzo.

In Spanish, nouns are often used with a definite article more often than in English. La póliza means the policy.

You can sometimes omit the article, but in a normal standalone sentence like this, la sounds natural and complete. Since póliza is a feminine singular noun, it takes la.

The accent mark shows where the stress goes: PÓ-li-za.

Without the accent, Spanish stress rules would make it sound different. The written accent tells you the stressed syllable clearly.

Because the verb is empezar and it has a stem change in the present tense: e → ie.

So:

• yo empiezo
• tú empiezas
• él/ella/usted empieza

But:

• nosotros empezamos
• vosotros empezáis
• ellos/ellas/ustedes empiezan

This is a very common pattern in Spanish. So empieza is the correct present-tense form for it starts / it begins.

Because the sentence is talking about when something begins, not what it is or how it is.

• ser = to be
• estar = to be
• empezar = to begin / to start

So La póliza empieza en marzo means the policy starts in March, not that it is in March.

Yes. Comienza from comenzar also means begins. Both are correct:

• La póliza empieza en marzo
• La póliza comienza en marzo

Empezar is extremely common in everyday speech. Comenzar is also common and may sound a little more formal in some contexts, but both work well.

Because Spanish uses en with months to mean in a month.

• en marzo = in March
• en abril = in April

So when you say when something happens during a month, en is the normal preposition.

Normally, no. In Spanish, months are usually written with a lowercase letter:

• marzo
• abril
• septiembre

So La póliza empieza en marzo is correct with marzo in lowercase.

A simple pronunciation guide is:

lah POH-lee-sah em-PYEH-sah en MAR-so

A few notes for Latin American Spanish:

• póliza → stress on pó
• empieza → stress on pie
• z in póliza is usually pronounced like s in Latin America
• marzo also usually has an s sound for the z in Latin America

In Spanish, months usually appear without an article after en when you are simply saying in March, in April, etc.

So:

• en marzo = in March
• en julio = in July

Using el here would not sound natural in this sentence.