Aldonu ajlon, herbojn kaj spicon.

Aldonu is the -u form of the verb aldoni, meaning to add.

The -u ending is used for:

• commands
• requests
• suggestions
• instructions

So in a recipe, Aldonu means Add.

The -n ending marks the direct object in Esperanto.

These are the things being added, so they take the accusative ending:

• ajlo → ajlon
• herboj → herbojn
• spico → spicon

In English, word order usually shows the object. In Esperanto, the -n ending helps show that job more clearly.

Because herbojn is plural, while ajlon and spicon are singular.

• herbo = herb
• herboj = herbs
• herbojn = herbs as a direct object

The sentence suggests:

• garlic as one ingredient/substance
• herbs as several herbs, or herbs in general
• spice as one spice, or spice/seasoning in general

This is not a special rule of recipes; it is just normal singular vs. plural usage.

The base forms are:

• aldoni = to add
• ajlo = garlic
• herbo = herb
• spico = spice
• kaj = and

The sentence uses changed forms because of grammar:

• aldoni → aldonu for a command
• ajlo → ajlon for the direct object
• herbo → herbojn for plural + direct object
• spico → spicon for the direct object

Because the sentence is talking about ingredients in a general recipe instruction, not specifically the garlic or the herbs in a strongly marked way.

La means the, and Esperanto uses it when something is definite. In recipe instructions, it is very common to leave it out:

• Aldonu ajlon = add garlic
• Aldonu la ajlon = add the garlic

The second version would sound more like you are referring to some particular garlic already identified in the situation.

It can mean either, depending on context.

In a recipe, singular nouns often refer to an ingredient in a general way, especially when the exact amount or type is understood from context. So spicon may mean:

• one spice
• some spice/seasoning
• a spice ingredient

If the writer wanted to emphasize several different spices, they might use spicojn instead.

No, Esperanto word order is fairly flexible, partly because the -n ending marks the objects.

Aldonu ajlon, herbojn kaj spicon is the most natural order for a recipe instruction: verb first, then the ingredients.

You could rearrange it, and the grammar would still work, but it might sound less neutral or less natural in an ordinary recipe.

Roughly:

ahl-DOH-noo AYE-lon HER-boyn kai SPEE-tson

A few helpful points:

• aj sounds like eye
• oj sounds like oy
• c is always like ts
• stress is on the second-to-last syllable of each word:
  • alDOnu
  • AJlon
  • HERbojn
  • kaj
  • SPIcon

So:

• Aldonu = al-DO-nu
• ajlon = AJ-lon
• herbojn = HER-bojn
• spicon = SPI-con

Kaj means and.

The sentence is simply listing ingredients:

• ajlon
• herbojn
• kaj spicon

So it works just like English and in a list. The commas separate the items, and kaj links the last one to the others.