Hieraŭ okazis malgranda akcidento sur tiu strato, ĉar unu aŭto turniĝis tro rapide.

Hieraŭ means yesterday, and it is an adverb of time. In Esperanto, word order is fairly flexible, so putting Hieraŭ first simply highlights the time.

You could also say:

Malgranda akcidento okazis hieraŭ sur tiu strato...

That would still be grammatical. Starting with Hieraŭ is very natural when the speaker wants to set the time frame first.

Okazis is the past tense of okazi, meaning to happen or to occur.

So okazis malgranda akcidento means a small accident happened / occurred.

If you used estis, that would mean was. Esperanto often prefers okazi for events, because accidents, meetings, festivals, and similar things typically happen rather than simply are.

So:

• okazis akcidento = an accident happened
• estis akcidento = there was an accident

Both can work in some contexts, but okazis is especially natural here.

mal- is a very common Esperanto prefix meaning the opposite of.

So:

• granda = big, large
• malgranda = small

This is one of the most useful building patterns in Esperanto. Instead of learning a completely unrelated word for the opposite, Esperanto often uses mal-.

Some other examples:

• bona = good → malbona = bad
• varma = warm → malvarma = cold
• alta = tall/high → malalta = short/low

Because malgranda describes the noun akcidento, so it must be an adjective.

In Esperanto:

• -a = adjective
• -e = adverb

Here, malgranda akcidento means a small accident, so malgranda has the adjective ending -a.

If you used malgrande, that would be an adverb, meaning something like smallly, which does not work here.

Compare:

• malgranda akcidento = a small accident
• rapide turniĝis = turned quickly

Because akcidento is the subject of okazis, not the direct object.

In Esperanto, the -n ending usually marks the direct object.

Here:

• malgranda akcidento okazis = a small accident happened

The accident is the thing doing the grammatical action of happening, so it is the subject and stays akcidento, not akcidenton.

If it were a direct object, then you would use -n.

sur usually means on. So sur tiu strato means on that street.

This is natural in Esperanto when talking about where something happened in relation to a street.

A learner may wonder about en. Sometimes en la strato can mean in the street, especially physically in the roadway. But sur tiu strato is a normal way to say that something happened on that street.

So the choice is mainly about normal usage and the kind of location being described.

Because this sentence describes location, not motion toward a place.

In Esperanto, -n can also show direction with prepositions:

• sur la tablo = on the table
• sur la tablon = onto the table

Here, the accident happened at a location: sur tiu strato. Nothing is moving onto the street, so there is no directional -n.

tiu means that.

So:

• tiu strato = that street
• la strato = the street

Use tiu when you want to point out a specific one, like that one there or that one we already know about.

Use la when you simply mean the in a definite sense.

So sur tiu strato is more specifically on that street, not just on the street.

ĉar means because. It introduces the reason:

ĉar unu aŭto turniĝis tro rapide
= because one car turned too quickly

This creates a cause-and-effect relationship:

• event: a small accident happened
• reason: a car turned too quickly

It is one of the most common conjunctions in Esperanto.

unu literally means one.

Esperanto has no indefinite article a/an, so sometimes a bare noun can already mean a car:

• aŭto = a car / car

But unu aŭto adds emphasis on one car or identifies one particular participant in the situation.

In context, it can sound like:

• one car
• a certain car
• one of the cars involved

So unu aŭto is not wrong or strange here; it simply gives a bit more focus.

This is about the suffix -iĝ-, which often makes a verb intransitive or gives the sense of becoming or undergoing a change.

• turni can mean to turn something
• turniĝi means to turn oneself / to turn / to make a turn

So:

• Li turnis la stirilon. = He turned the steering wheel.
• La aŭto turniĝis. = The car turned.

In this sentence, the car itself is making the turn, so turniĝis is very natural.

Also, -is shows past tense, so turniĝis = turned.

rapide means quickly, and tro means too, in the sense of excessively.

So tro rapide means:

• too quickly
• overly fast

It implies that the speed was more than was safe or appropriate.

Also notice that rapide ends in -e because it describes the verb turniĝis. It tells us how the car turned.

Compare:

• rapida aŭto = a fast car
• la aŭto turniĝis rapide = the car turned quickly

The main special letters here are:

• ĉ in ĉar: like ch in church
• ĝ in turniĝis: like j in judge
• ŭ in aŭto and hieraŭ: a short glide, similar to the w-sound in English cow or how

So roughly:

• ĉar ≈ char
• aŭto ≈ OW-to
• hieraŭ ≈ hee-eh-ROW
• turniĝis ≈ toor-NEE-jis

Exact pronunciation depends on accent, but those approximations are close enough for a beginner.