La planificación de menús reduce el desperdicio alimentario.

Because planificación is a feminine singular noun, so it takes the feminine singular definite article la.

• la planificación = the planning
• The ending -ción is very often feminine in Spanish:
  • la información
  • la educación
  • la organización

So La planificación is grammatically required here, just like the planning in English.

Both can refer to planning, but planificación is the more standard and common choice in Spain.
A learner of Spanish from Spain should definitely recognize and prefer planificación in this kind of formal or neutral sentence.

• planificación = common in Spain
• planeación = more common in some parts of Latin America

So in European Spanish, La planificación de menús sounds very natural.

De menús means of menus or, more naturally in English, menu planning.

Spanish often uses the structure:

• noun + de + noun

So:

• la planificación de menús = the planning of menus = menu planning

This is very common in Spanish. A few similar examples:

• plan de estudios = study plan / curriculum
• lista de compras = shopping list
• control de calidad = quality control

It is plural because the sentence is talking about menu planning in general, not planning one single menu.

The singular is:

• menú

The plural is:

• menús

The written accent stays because the word still needs stress on the final syllable.

Compare:

• menú → menús
• tabú → tabús

So menús is the correct plural form.

Because Spanish often leaves out the article in phrases like this when the second noun is being used in a general, classifying way.

• la planificación de menús = menu planning in general

If you said la planificación de los menús, it would usually refer to specific menus, for example the menus of a particular school, restaurant, or week.

So:

• de menús = menus in general
• de los menús = those particular menus

Because reduce is the conjugated verb, while reducir is the infinitive.

The subject is La planificación de menús, which is grammatically third person singular, so the verb must also be third person singular in the present tense:

• reducir = to reduce
• reduce = it reduces

So the sentence literally works as:

• La planificación de menús = menu planning
• reduce = reduces
• el desperdicio alimentario = food waste

Because the subject is not menús. The subject is the whole phrase La planificación de menús, and the main noun in that phrase is planificación, which is singular.

Think of it like English:

• Menu planning reduces food waste

Even though menus is plural inside the phrase menu planning, the subject is still planning, which is singular.

So Spanish uses:

• La planificación... reduce not
• La planificación... reducen

It means food waste.

• desperdicio = waste / wastage
• alimentario = related to food, diet, or food supply

Together, desperdicio alimentario is a common formal expression for food waste.

You may also hear:

• desperdicio de alimentos

This means almost the same thing and is often a bit more transparent for learners because it is literally waste of food(s).

Because alimentario is the standard adjective used here in Spanish to mean food-related.

It agrees with desperdicio, which is masculine singular, so the adjective must also be masculine singular:

• el desperdicio alimentario

Other forms would change depending on the noun:

• la industria alimentaria = the food industry
• los residuos alimentarios = food waste / food residues

So the form changes for agreement, but the base adjective is alimentario.

Because desperdicio is a masculine singular noun, so it takes el.

• el desperdicio
• el desperdicio alimentario

This is just standard article-noun agreement:

• masculine singular → el
• feminine singular → la

Yes, but the meaning changes slightly.

• La planificación de menús = menu planning in general
• La planificación del menú = the planning of the menu / a specific menu

So the original sentence sounds broader and more general, which is probably why it uses de menús.

Yes, more or less. In Spanish, abstract or mass concepts are often expressed in the singular.

• el desperdicio alimentario = food waste as a general phenomenon

This is similar to English, where waste is often uncountable.

You could use a plural in other contexts, but here the singular is the natural choice.

In standard peninsular Spanish, reduce is pronounced roughly like reh-DOO-theh or reh-DOO-seh, depending on accent.

Important points:

• the r is a soft tapped r
• the du sounds like doo
• the c before e is usually pronounced like the th in thin in much of Spain

So in much of Spain:

• reduce → reh-DOO-theh

In Latin American pronunciation, the c before e would usually sound like s:

• reh-DOO-seh

It is possible, but it sounds more marked or emphatic.

The normal, neutral order is:

• La planificación de menús reduce el desperdicio alimentario.

If you move things around, you usually create emphasis or a more literary tone:

• El desperdicio alimentario lo reduce la planificación de menús.

That version highlights food waste more strongly, but it is not the most natural basic wording for a learner to use first.

It sounds fairly neutral to formal.

Words like:

• planificación
• desperdicio alimentario

are common in informative, educational, institutional, or environmental contexts.

In more everyday speech, someone might say something simpler, such as:

• Planificar los menús reduce el desperdicio de comida.

That sounds a bit more conversational, while the original sentence sounds polished and informative.