Je garde cet exemple dans mon cahier pour le revoir plus tard.

French usually uses the simple present (je garde) where English uses either I keep or I’m keeping.

• Je garde cet exemple… can mean:
  • I’m keeping this example… (an action happening now), or
  • I keep this example… (a general habit).

The form être en train de + infinitive (e.g. je suis en train de garder) exists, but it’s only used when you really want to insist on “right now, at this moment”. In most contexts, je garde is the natural choice.

In this sentence, garder means to keep / to hold on to / not to throw away.

• Je garde cet exemple… = I’m keeping this example…
  → I’m not deleting it; I’m keeping it in my notebook.

Compare:

• conserver – more formal or technical: conserver des données, conserver des aliments.
• tenir – more physical: tenir un livre (to hold a book).
• garder (for children / pets): garder les enfants, garder le chien = to look after, to babysit.

The core idea of garder is keeping something in your possession or under your care. In the context of a notebook, garder un exemple is completely natural.

Cet is the masculine singular demonstrative adjective used before a vowel sound:

• ce
  • consonant: ce livre (this book)
• cet
  • vowel or mute h: cet exemple, cet homme
• cette
  • any sound, but feminine: cette idée, cette femme

Exemple is masculine, so we would normally use ce:
→ ce exemple in theory, but because exemple starts with a vowel, it becomes cet exemple for ease of pronunciation.

So:

• cet exemple = this example (masculine, starts with a vowel)

You can see that exemple is masculine from:

• cet exemple (masculine demonstrative)
• later, le in pour le revoir (masculine direct object pronoun)

Because exemple is masculine:

• we say cet exemple (not cette exemple)
• we refer back to it with le (not la)

If exemple were feminine, the sentence would be:

• Je garde cette phrase dans mon cahier pour la revoir plus tard.
  (phrase is feminine, so cette and la.)

Here le is not an article. It is a direct object pronoun meaning it.

It stands for cet exemple:

• Je garde cet exemple… pour le revoir plus tard.
  → le = cet exemple

So le revoir literally means to see it again / to review it.

Articles (like le livre) go before nouns.
Object pronouns (like le voir) go before verbs and replace a noun.

In French, object pronouns normally come before the verb they depend on:

• le revoir = to see/review it again
• le lire = to read it
• la comprendre = to understand it (feminine)

The pattern is:

• pour
  • pronoun
    • infinitive

Examples:

• pour le lire plus tard – to read it later
• pour la regarder demain – to watch it tomorrow

So you cannot say pour revoir le. The correct order is pour le revoir.

Garde is the present indicative, 1st person singular (je garde).

French present covers several English uses:

• I keep this example… (habit)
• I’m keeping this example… (current action / decision)

The sentence doesn’t force one or the other; context decides. The form itself is just the neutral present.

Dans is used for inside something, and here the idea is inside the notebook (on its pages):

• dans mon cahier = in my notebook

Alternatives:

• sur mon cahier = physically on top of the notebook (e.g. a pen on it), not written in it.
• en cahier is not idiomatic; you wouldn’t say en mon cahier in this context.

For written notes, French typically uses:

• dans mon cahier, dans mon carnet, dans mon agenda.

Because cahier is masculine. Possessive adjectives must agree with the gender (and number) of the noun, not with the owner.

• mon cahier – my notebook (masculine)
• ma trousse – my pencil case (feminine)
• mes cahiers – my notebooks (plural)

Even if the speaker is a woman, it is still mon cahier, because cahier is grammatically masculine.

Pour + infinitive often expresses purpose, like to / in order to in English.

• pour le revoir plus tard = to review it later / in order to review it later

Structure:

• pour
  • (object pronoun, if any)
    • infinitive

Examples:

• Je viens pour t’aider. – I’m coming (in order) to help you.
• Elle garde ses notes pour les relire. – She keeps her notes to reread them.

So pour le revoir answers Why are you keeping this example?

Yes, grammatically you can say:

• Je garde cet exemple dans mon cahier pour revoir cet exemple plus tard.

But it sounds repetitive. Native speakers usually avoid repeating the noun and use a pronoun:

• Je garde cet exemple… pour le revoir plus tard.

Both mean the same thing; using le just makes the sentence more natural and less heavy.

The usual and most natural place is at the end:

• pour le revoir plus tard

You could also occasionally hear:

• pour plus tard le revoir – grammatical but sounds literary/unnatural in everyday speech.

Putting plus tard in the middle of le revoir would be wrong. So for normal speech, keep:

• pour le revoir plus tard

• revoir = literally to see again; by extension to review / to go over again.
  
  • revoir un exemple, une leçon – look at it again, review it.
• réviser = to revise / to study / to review for an exam. More academic or exam-related.
  • réviser un examen, réviser sa grammaire.
• relire = to read again.
  • relire un texte, relire une page.

In your sentence, revoir is good because you’re going back to the example to look at it again and understand/remember it. You might also say pour le réviser plus tard, but that sounds a bit more like exam-style revision.