Se vi verŝas sukon sur la planko, vi viŝu ĝin kaj poste balau la ĉambron.

Because this sentence is giving a general instruction: if/whenever you spill juice on the floor, do this.

In Esperanto, a present tense verb after se often expresses a general or repeated condition:

• Se vi verŝas... = If you spill / If ever you spill / Whenever you spill...

If you said Se vi verŝos..., that would point more to a specific future case:

• Se vi verŝos... = If you will spill... / If you happen to spill later...

So verŝas fits the idea of a general rule.

The ending -u is the volitive ending in Esperanto. It is used for:

• commands
• instructions
• requests
• recommendations
• wishes

So:

• viŝu = wipe
• balau = sweep

In this sentence, the speaker is telling someone what they should do in that situation. That is exactly the kind of meaning -u is used for.

Yes, viŝu ĝin would also be correct.

Esperanto often leaves out the subject in a command because it is already understood. So:

• Viŝu ĝin = Wipe it
• Balau la ĉambron = Sweep the room

But adding vi makes the subject explicit:

• vi viŝu ĝin = you should wipe it

This can sound a bit more pointed, more explicit, or simply clearer after the se clause. It is not wrong at all; it just makes the instruction specifically directed at you.

ĝin refers to sukon — the juice.

So the meaning is:

• spill the juice
• wipe it up

Grammatically:

• ĝi = it
• ĝin = it as a direct object

The -n appears because the pronoun is receiving the action of viŝu.

Because sukon is the direct object of verŝas.

In Esperanto, the direct object usually takes -n:

• verŝi sukon = to pour/spill juice
• mi vidas la hundon = I see the dog
• ŝi legas libron = she reads a book

In your sentence:

• vi verŝas sukon = you spill juice

So suko becomes sukon.

This is a very common learner question.

With place prepositions like sur, Esperanto can sometimes distinguish between:

• location: sur la planko = on the floor
• direction toward that place: sur la plankon = onto the floor

Many learners expect sur la plankon here, because the juice moves onto the floor. That form is also very natural.

But sur la planko is understandable too, because it presents the floor as the place where the spilled juice is. In real usage, speakers may choose one or the other depending on whether they want to emphasize movement toward the surface or simply the resulting location.

So:

• sur la planko = focuses on the place
• sur la plankon = focuses more on motion onto it

Because the speaker means a specific floor and a specific room — the ones relevant in the situation.

So:

• la planko = the floor (the floor here, the one in question)
• la ĉambron = the room (the room you are in / the room being discussed)

Esperanto uses la much like English the. In practical instructions like this, it is very natural to use la when both speaker and listener know which floor and room are meant.

Because la ĉambron is the direct object of balau.

The verb balai is transitive, so it can take a direct object:

• balai la ĉambron = to sweep the room
• balai la plankon = to sweep the floor

That is why ĉambro becomes ĉambron.

Because in Esperanto, balai usually works directly on the thing being swept.

So Esperanto says:

• balai la ĉambron = sweep the room
• balai la plankon = sweep the floor

You do not need a preposition there. The room itself is treated as the object of the sweeping action.

They refer to different kinds of cleaning actions.

• viŝi = to wipe

  • usually with a cloth, rag, towel, mop, etc.
  • used for removing liquid, dirt, marks, and so on

• balai = to sweep

  • usually with a broom
  • used for dust, crumbs, debris, etc.

So the sentence gives two steps:

1. viŝu ĝin — wipe up the spilled juice
2. balau la ĉambron — then sweep the room

Poste means afterwards / then. It marks the order of actions.

In this sentence:

• vi viŝu ĝin kaj poste balau la ĉambron
• wipe it and then sweep the room

Esperanto word order is fairly flexible, so poste can sometimes move, but its position here is very natural because it clearly shows the second action comes after the first one.

Because Se vi verŝas sukon sur la planko is a subordinate if-clause, and it is followed by the main clause.

So the structure is:

• Se ... , ...

This is normal punctuation in Esperanto, just as in English:

• If you spill juice on the floor, wipe it up...

The comma helps separate the condition from the instruction that follows.