Il ne l’a pas fait exprès, il a seulement oublié la sauce sur la table.

French object pronouns usually go before the conjugated verb. Here, l’ is a direct object pronoun, and a is the conjugated form of avoir.

So the order is:

• Il
• ne
• l’
• a
• pas
• fait exprès

That is the normal pattern for negation with an object pronoun in a compound tense:

• subject + ne
  • object pronoun + auxiliary verb + pas
    • past participle

So:

• Il ne l’a pas fait exprès = He didn’t do it on purpose

L’ stands for le or la, depending on what earlier thing is being referred to. In English, it means it or sometimes him/her, but here it most naturally means it.

So:

• Il ne l’a pas fait exprès = He didn’t do it on purpose

The sentence does not repeat what l’ refers to, because it is already understood from context.

The apostrophe shows elision, which happens when a word like le or la comes before a vowel sound.

So:

• le a is not possible
• la a is not possible
• both become l’a

This is just the normal written form before a vowel.

Faire exprès is a fixed expression meaning to do something on purpose or deliberately.

Examples:

• Tu l’as fait exprès ? = Did you do it on purpose?
• Je n’ai pas fait exprès. = I didn’t do it on purpose.

So in your sentence:

• Il ne l’a pas fait exprès = He didn’t do it deliberately.

You should learn faire exprès as a whole expression, not try to translate each word literally.

This is the passé composé of faire.

The verb faire uses avoir in the passé composé:

• j’ai fait
• tu as fait
• il a fait

So:

• Il a fait exprès = He did it on purpose
• Il ne l’a pas fait exprès = He didn’t do it on purpose

The word fait is the past participle of faire.

Because with avoir, the past participle usually does not agree with the direct object if that object comes after the verb.

Here:

• a oublié = has forgotten / forgot
• la sauce comes after the verb

So it stays:

• oublié

If the direct object came before the verb, agreement could happen:

• La sauce qu’il a oubliée...

But in your sentence:

• il a seulement oublié la sauce sur la table

there is no agreement, so oublié is correct.

Seulement means only or just.

In this sentence, it softens or limits what happened:

• il a seulement oublié la sauce sur la table
• he only / just forgot the sauce on the table

It suggests that the action was minor or accidental, which fits well with the first clause:

• He didn’t do it on purpose; he just forgot the sauce on the table.

French adverbs often go around the verb, and in compound tenses they commonly appear between the auxiliary and the past participle, or just before the past participle.

So:

• il a seulement oublié...

is a normal placement.

You may also hear or see other adverb placements depending on emphasis, but this version is very natural.

Sur la table means on the table.

So:

• oublier la sauce sur la table = to leave/forget the sauce on the table

In English, we often say He left the sauce on the table. French can express that idea with oublier plus the thing and location.

So the second clause means that he accidentally left the sauce there.

The sentence has two linked ideas:

1. Il ne l’a pas fait exprès
   = He didn’t do it on purpose

2. il a seulement oublié la sauce sur la table
   = he only/just forgot the sauce on the table

The second part explains the first. In other words, it gives the reason why we should not think it was deliberate.

In more formal writing, some people might prefer a semicolon or a conjunction such as car or parce que, but the comma is very natural in everyday style.

Yes, often you can.

• Il n’a pas fait exprès = He didn’t do it on purpose
• Il ne l’a pas fait exprès = He didn’t do it on purpose

The version with l’ is more specific because it points back to a particular action or event already mentioned. Without l’, the meaning is still clear in many situations, but it is a little less explicit.

In careful written French, yes:

• Il ne l’a pas fait exprès

In informal spoken French, people often drop ne:

• Il l’a pas fait exprès

That is very common in speech, but learners should still know the full standard form for writing and formal contexts.

A natural translation would be something like:

• He didn’t do it on purpose; he just forgot the sauce on the table.

Depending on context, you might also say:

• He didn’t mean to do it; he just left the sauce on the table.

That second version is not word-for-word, but it often matches the intended meaning very well.