Секретарь секции подготовил сертификат участника.

Секретарь is the subject because it is in the nominative case, and the verb подготовил agrees with it.

A few clues help:

• подготовил = past tense, masculine singular
• секретарь is the noun that matches that verb
• сертификат is the direct object here

In English, word order usually tells you who did what. In Russian, case and verb agreement do much more of that work.

So this sentence means:

• The secretary of the section prepared the participant's certificate

not

• The certificate prepared the secretary

even though сертификат looks similar to a nominative form. For an inanimate masculine noun, the accusative singular is the same as the nominative, so сертификат can be either form depending on context.

In Russian, nouns ending in -ь can be either masculine or feminine. You usually have to learn the gender word by word.

• секретарь is normally treated as a masculine noun
• That is why the past tense verb is подготовил, not подготовила

If the secretary were female, Russian often says:

• Секретарь секции подготовила сертификат участника.

So the noun itself stays the same, but the past tense verb can show the person's sex.

Because секции is in the genitive singular and means of the section.

So:

• секретарь = secretary
• секции = of the section

Together, секретарь секции means:

• the secretary of the section
• or, depending on context, the section secretary

This is a very common Russian pattern: one noun followed by another noun in the genitive to show a relationship like of, belonging to, or associated with.

Base form:

• секция = section

Genitive singular:

• секции = of the section

Подготовил is the perfective past tense of подготовить, and it usually means the action was completed.

So:

• подготовил = prepared / got ready / completed the preparation of

By contrast:

• готовил is from готовить (imperfective)
• It focuses more on the process, repeated action, or ongoing activity
• It can mean was preparing or prepared in a less result-focused way

Here, подготовил is natural because the sentence is about a completed result: the certificate is ready.

Because сертификат is the direct object in the accusative singular, and for an inanimate masculine noun, the accusative looks exactly like the nominative.

So:

• nominative: сертификат
• accusative: сертификат

That is normal for masculine inanimate nouns.

If it were a feminine noun, you would usually see a clearer change, for example:

• подготовил справку
  here справка becomes справку in the accusative

Участника is genitive singular of участник.

Here it depends on сертификат:

• сертификат участника = certificate of a participant / participant's certificate

This is another example of the very common Russian noun + genitive noun pattern.

So the sentence contains two such relationships:

• секретарь секции = secretary of the section
• сертификат участника = certificate of the participant / participant's certificate

It can suggest either idea, and context decides.

Most naturally, сертификат участника means something like:

• a participant's certificate
• a certificate issued to/for a participant
• a certificate confirming someone was a participant

In many real situations, this phrase is understood as a type of certificate, not just random possession.

So it is often closer to:

• certificate of participation
• or participant certificate

depending on the exact context.

Russian has no articles like English the and a/an.

So Russian often leaves it to context whether something is:

• a secretary or the secretary
• a certificate or the certificate
• a participant or the participant

In this sentence, English translation might use:

• The secretary of the section prepared the participant's certificate
• or A section secretary prepared a participant certificate

Which one sounds best depends on the wider context.

No. Russian word order is much freer than English word order.

The neutral order here is:

• Секретарь секции подготовил сертификат участника.

But other orders are possible, for example to change emphasis:

• Сертификат участника подготовил секретарь секции.
  This puts more focus on the participant's certificate

• Секретарь секции сертификат участника подготовил.
  This can sound more marked or conversational

Even when word order changes, the cases still help show the relationships between the words.

They are:

• секретарь = secretary
• секция = section
• подготовить = to prepare
• сертификат = certificate
• участник = participant

Forms used in the sentence:

• секретарь = nominative singular
• секции = genitive singular of секция
• подготовил = past tense, masculine singular of подготовить
• сертификат = accusative singular
• участника = genitive singular of участник

The stress is:

• секрета́рь
• се́кции
• подготови́л
• сертифика́т
• уча́стника

So the full sentence is pronounced:

• секрета́рь се́кции подготови́л сертифика́т уча́стника

Stress is important in Russian because it is not always predictable and can change from one form to another.