Ni transplantas la planton hodiaŭ.

Because la planton is the direct object of the verb: it is the thing being transplanted.

In Esperanto, direct objects usually take the accusative ending -n.

• planto = plant
• planton = plant as a direct object

So in Ni transplantas la planton hodiaŭ, ni is doing the action, and la planton receives the action.

La is the definite article, meaning the.

So:

• la planton = the plant
• planton = a plant / plants depending on context

Esperanto has only one article, la, and it never changes form. It does not matter whether the noun is singular, plural, subject, or object: the article stays la.

Because in Esperanto, the article la is invariable. It always stays la.

Only the noun and any matching adjectives take endings like:

• -n for the accusative
• -j for the plural
• -jn for plural accusative

So you would say:

• la planto = the plant
• la planton = the plant as object
• la plantoj = the plants
• la plantojn = the plants as object

But the article remains la every time.

The ending -as marks the present tense.

So transplantas means something like:

• transplant
• am transplanting
• are transplanting
• do transplant

Which English version is best depends on context.

Esperanto does not normally use a separate helping verb like are to make the progressive. The simple present -as can cover both we transplant and we are transplanting.

Because Esperanto does not build the normal present progressive the same way English does.

English often uses:

• we transplant
• we are transplanting

Esperanto usually uses just the main verb in the present tense:

• Ni transplantas

That form can express either a simple present or an ongoing present action, depending on context.

There is a participle-based way to be more explicit, but in ordinary speech Ni transplantas is the normal way.

Yes. Hodiaŭ is an adverb meaning today, and Esperanto word order is fairly flexible.

All of these are possible:

• Ni transplantas la planton hodiaŭ.
• Hodiaŭ ni transplantas la planton.
• Ni hodiaŭ transplantas la planton.

The most natural choice depends on what you want to emphasize.

Putting hodiaŭ at the end is completely normal.

Because hodiaŭ is an adverb, not a direct object.

The -n here is used on the noun that receives the action: planton.

In Esperanto, some time expressions can sometimes take -n in certain uses, but hodiaŭ is already an adverbial word, so it does not need any extra ending here.

Yes. That is grammatically correct.

Because la planton has the accusative -n, it is clear that it is the object, so the sentence can be rearranged more freely than in English.

Still, some orders sound more natural than others depending on context. The original sentence is straightforward and natural.

It can be broken into parts:

• trans- = across / from one place to another
• plant- = plant
• -as = present tense verb ending

So transplantas literally has the idea of transplanting or moving a plant to another place.

This kind of word-building is very common in Esperanto and is one of the language’s most useful features.

A simple English-friendly approximation is ho-dee-OW.

A few points:

• ho as in hope without the final glide
• di like dee
• aŭ sounds roughly like ow in now

The last part, aŭ, is a diphthong. The letter ŭ is very short and combines with the vowel before it.

So hodiaŭ is approximately ho-di-ow.

Normally, no. Esperanto personal pronouns do not change as much as English pronouns do, but they can take -n if they are direct objects.

So:

• ni = we
• nin = us

In this sentence, ni is the subject, so it stays ni.

Example:

• Ni transplantas la planton. = We transplant the plant.
• Li vidas nin. = He sees us.

You would add the plural ending -j.

• la planto = the plant
• la plantoj = the plants

And because the object also needs -n, you would combine them:

• la plantojn = the plants as a direct object

So:

• Ni transplantas la plantojn hodiaŭ. = We are transplanting the plants today.

The order of endings is important:

• noun + -j
  • -n
• so planto + j + n = plantojn