La monnaie est dans mon sac, alors je paie tout de suite.

La monnaie often means change or coins, not just money in the broad sense.

In this sentence, it suggests that the speaker has the cash/change needed to pay. A native English speaker might expect argent, because argent is the most common word for money in general.

A useful distinction is:

• l’argent = money in general
• la monnaie = coins, small change, or change received/given in a transaction

So this sentence sounds a bit like: I have the change/cash in my bag, so I’m paying right away.

French usually needs an article before a noun, where English often does not.

So French says:

• La monnaie est dans mon sac
• literally: The change is in my bag

Even when English would just say Money is in my bag or I have change in my bag, French normally keeps the article.

Here la monnaie refers to a specific thing the speaker has available.

Because sac is a masculine noun in French.

So the possessive adjective must match the noun:

• mon sac = my bag
• ma voiture = my car
• mes livres = my books

The possessive agrees with the thing possessed, not with the gender of the speaker.

So even a woman would say mon sac.

Sac is a general word for bag.

Depending on context, it could mean:

• a handbag
• a backpack
• a shopping bag
• a regular bag

French often uses broader words than English, and the exact type is understood from the situation.

Here alors means so, then, or in that case.

It links the two ideas:

• La monnaie est dans mon sac = the money/change is in my bag
• alors je paie tout de suite = so I’ll pay right away

So alors introduces the consequence or result.

Both je paie and je paye are correct.

They are two accepted spellings/forms of the verb payer in the present tense:

• je paie
• je paye

You may also see:

• il paie / il paye
• ils paient / ils payent

In modern French, paie is very common, but paye is also standard.

French often uses the present tense to talk about something that is about to happen, especially when it feels immediate.

So:

• je paie tout de suite

can mean:

• I’m paying right away
• I’ll pay right away

The present tense makes the action sound direct and immediate.

If you said je paierai tout de suite, it would also be possible, but it may sound a little more explicitly future-oriented.

Tout de suite is a very common fixed expression meaning:

• right away
• immediately
• at once

So:

• je paie tout de suite = I’m paying right away

Do not translate it word by word too literally. It functions as one expression.

Because tout de suite is an idiomatic fixed phrase. You generally learn it as a whole unit.

Even though learners may want to analyze each word separately, the safest approach is:

• memorize tout de suite = right away / immediately

French has many expressions like this where the preposition is just part of the set phrase.

Here it comes after the verb:

• je paie tout de suite

That is the normal position for this kind of adverbial expression.

French word order is often:

• subject + verb + adverb/expression

So:

• je mange maintenant
• je pars tout de suite
• je paie tout de suite

A rough guide for English speakers:

• monnaie ≈ moh-NAY
• paie ≈ peh

More precisely:

• monnaie sounds like mon-è
• paie rhymes roughly with met in many accents, though not perfectly

A full rough pronunciation of the sentence is:

• La monnaie est dans mon sac, alors je paie tout de suite.
• lah moh-NAY eh dahn mon sak, ah-LOR zhuh peh too duh sweet

The j in je is the soft sound heard in measure.

In a normal statement, French usually requires the subject pronoun:

• je paie tout de suite

Unlike English, which can sometimes drop words informally, standard French generally keeps the subject.

You can omit it in very informal notes, messages, or commands, but in a regular full sentence, je is expected.

Yes. A very natural alternative would be:

• J’ai de la monnaie dans mon sac.

That means I have some change in my bag.

This version may sound more natural in many everyday situations, because English speakers often think in terms of having something rather than it is in my bag.

But the original sentence is still grammatically correct and understandable.