Learn Hardcore French: Je garde le billet dans mon sac.

J’ai le billet dans mon sac would mean I have the ticket in my bag, simply stating possession.
Je garde le billet dans mon sac adds the idea that you are deliberately keeping it there (for safety, for later use, etc.).

How would I say I am keeping the ticket in my bag vs I keep the ticket in my bag in French?

In French, the simple present je garde covers both English forms:

Je garde le billet dans mon sac.
= I am keeping the ticket in my bag.
= I keep the ticket in my bag.

French does not normally use a special continuous form like English I am keeping.
If you really want to emphasize the ongoing action, you can say:

Je suis en train de garder le billet dans mon sac.
(literally: I am in the process of keeping…)

But in most everyday situations, je garde is enough for both meanings.

Why is it le billet and not un billet?

Le billet = the ticket, referring to a specific, identified ticket.
Un billet = a ticket, introducing a ticket not yet known or not specific.

In this sentence, the speaker is almost certainly talking about a particular ticket (for example, the one you have just bought, or the one for tonight’s concert). That is why French uses the definite article le.

French also tends to use definite articles more often than English, so le billet is very natural once the object is known in the conversation.

What does billet mean here, and can it mean other things?

In this sentence, billet means ticket (for a train, concert, plane, etc.).

Other common uses of billet:

un billet de train – a train ticket
un billet d’avion – a plane ticket (often un billet in speech)
un billet de banque – a banknote / bill (paper money)
In informal language: un billet can sometimes just mean a banknote (e.g. un billet de 20 euros).

There is also the English-looking word un ticket in French, but it is used more in some specific contexts (parking ticket, cashier’s receipt, some transport systems), and usage varies by region.

Why is it mon sac and not just le sac?

mon sac = my bag, so you specify whose bag it is.
le sac = the bag, which could be any bag known from context.

In everyday speech, when you talk about something that belongs to you (your bag, your car, your phone), French very often uses a possessive adjective:

Je garde le billet dans mon sac. – I keep the ticket in my bag.

Using le sac without any context could sound incomplete or unclear, as if you were referring to some particular bag everyone already knows about.

Why is it mon sac and not ma sac?

Because sac is a masculine noun in French: un sac.

Masculine singular: mon sac, ton sac, son sac
Feminine singular: ma valise, ta valise, sa valise
Plural (for both genders): mes sacs, tes valises

So the form ma sac is grammatically incorrect. You must say mon sac.

Why is the preposition dans used here, and could I say something else for in my bag?

Dans is the standard preposition for in / inside a place or container:

dans mon sac – in my bag
dans la boîte – in the box

Other possibilities:

à l’intérieur de mon sac – inside my bag (more explicit, less common in simple sentences like this)
sur mon sac – on my bag (physically on top of it, different meaning)

You would not say en mon sac; that is not idiomatic modern French. For in my bag, dans mon sac is the natural choice.

Can I change the word order, for example Je garde dans mon sac le billet?

The usual, most natural order is:

Je garde le billet dans mon sac.
subject – verb – direct object – prepositional phrase

Je garde dans mon sac le billet is grammatically possible but sounds marked or stylistic, as if you were emphasizing in my bag or the ticket in a special way (for poetic or rhetorical effect).

For normal conversation or writing, stick with: Je garde le billet dans mon sac.

How would I replace le billet with a pronoun in this sentence?

Le billet is a masculine singular direct object, so the corresponding direct object pronoun is le.

It goes before the conjugated verb:

Je garde le billet dans mon sac.
→ Je le garde dans mon sac. – I keep it in my bag.

Note that word order in French is:
subject pronoun + object pronoun + verb + rest of the sentence.

In French, can I drop je like in Spanish and just say garde le billet dans mon sac?

No. In standard French, the subject pronoun (je, tu, il, elle, nous, vous, ils, elles) is almost always required.

So you must say:

Je garde le billet dans mon sac.

Simply Garde le billet dans mon sac would be understood as an imperative (a command): Keep the ticket in my bag. That is a different meaning and a different structure.

How is Je garde le billet dans mon sac pronounced, and are there any silent letters?

Approximate pronunciation: [ʒə gaʁd lə bijɛ dɑ̃ mɔ̃ sak]

Key points:

Je – sounds like zhuh.
garde – gar-d, final e is silent; the d is pronounced.
le – luh.
billet – bee-yɛ, the final t is silent.
dans – dɑ̃, the final s is silent, nasal vowel ɑ̃.
mon – mɔ̃, nasal on sound.
sac – sak, all letters pronounced.

There is a small liaison possibility between garde and le (some speakers slightly link the d and l), but no extra consonant is added; the main silent letters are e in garde, t in billet, and s in dans.