Mi staris apud la breto, dum ŝi frapis la najlon per martelo.

In Esperanto, -is is the past-tense verb ending. It works for all verbs.

• stari = to stand

• staris = stood / was standing

• frapi = to strike, hit
• frapis = struck / hit

So both actions are described as happening in the past.

Esperanto does not force the same distinction that English often makes between I stood and I was standing. The simple past -is can cover both, depending on context.

So Mi staris apud la breto can mean:

• I stood by the shelf
• I was standing by the shelf

In this sentence, because another action happens at the same time, English naturally prefers I was standing.

Apud means beside, next to, or by in the sense of physical closeness.

So:

• apud la breto = beside the shelf / by the shelf

It suggests location near something. It is more specific than a very general word like ĉe, which often just means at or with.

La is the definite article, meaning the.

So:

• breto = a shelf / shelf
• la breto = the shelf

Esperanto uses la when the speaker is referring to a specific thing. There is no separate word for a or an in Esperanto.

Dum means while or during the time that.

In this sentence, it connects two actions that were happening at the same time:

• Mi staris apud la breto
• ŝi frapis la najlon per martelo

So dum shows simultaneity: one thing was happening while another thing was happening.

Ŝi means she.

The first letter, ŝ, is a normal Esperanto letter, pronounced like English sh. So ŝi sounds like shee.

Esperanto has several letters with diacritics, and they are considered separate letters, not just decorative versions of ordinary ones.

The -n marks the direct object in Esperanto. The direct object is the thing directly affected by the verb.

Here:

• ŝi frapis = she hit
• la najlon = the nail

The nail is what she hit, so it gets -n:

• najlo = nail
• la najlon = the nail as a direct object

This is one of the most important grammar markers in Esperanto.

Because martelo is not the direct object here. It is the instrument used to perform the action.

Per means with, in the sense of by means of or using.

So:

• frapis la najlon = hit the nail
• per martelo = with a hammer

The direct object is la najlon, so that gets -n.
After the preposition per, the noun normally does not take -n.

Esperanto has a word for the — la — but it does not have an indefinite article like English a or an.

So:

• martelo can mean a hammer or just hammer, depending on context
• la martelo means the hammer

That is why per martelo naturally means with a hammer.

Yes, Esperanto word order is fairly flexible, especially because the -n ending shows which noun is the direct object.

For example, these would still be understandable:

• Dum ŝi frapis la najlon per martelo, mi staris apud la breto.
• Mi staris apud la breto, dum per martelo ŝi frapis la najlon.

However, the original order is the most natural and straightforward.

Here are the main forms:

• mi = I
• stari = to stand
• apud = beside, next to
• la = the
• breto = shelf
• dum = while
• ŝi = she
• frapi = to strike, hit
• najlo = nail
• per = with, by means of
• martelo = hammer

In the sentence, some of these are changed by grammar endings:

• staris = past tense of stari
• frapis = past tense of frapi
• najlon = najlo
  • object ending -n

Yes, it is completely normal.

The structure is:

• verb
• direct object
• instrument with per

So:

• frapis = hit
• la najlon = the nail
• per martelo = with a hammer

This is a very common Esperanto pattern, and it works much like English hit the nail with a hammer.