Después de pagar la cuenta, guardo el resto del dinero en la cartera.

Because after después de, Spanish normally uses de + infinitive when the same person does both actions.

So:

• Después de pagar la cuenta... = After paying the bill...

Using pago there would be wrong, because pago is a conjugated verb form, not an infinitive.

If you wanted a different subject, Spanish would usually switch to a full clause, for example:

• Después de que él paga/pague... depending on context

But in your sentence, the person who pays is also the person who puts the money away, so pagar is the natural choice.

Here, la cuenta means the bill or the check, especially in a restaurant, café, or bar.

In Spain, pedir la cuenta is the normal way to say ask for the bill/check.

It does not usually mean a financial invoice in this kind of everyday context. For a more formal invoice, Spanish often uses la factura.

So in this sentence, pagar la cuenta is the normal everyday phrase for pay the bill.

Guardo is:

• first person singular
• present tense
• from the verb guardar

So it means I keep, I put away, or I store, depending on context.

Without more context, this sentence sounds like either:

• a habitual action: After paying the bill, I put the rest of the money in my wallet
• or a simple present narration

The ending -o tells you the subject is I.

Because Spanish often leaves subject pronouns out when the verb ending already makes the subject clear.

• guardo already means I keep / I put away
• so yo guardo is usually unnecessary

Spanish uses yo only when it wants emphasis, contrast, or extra clarity.

For example:

• Yo guardo el dinero, pero él lo gasta.
  I put the money away, but he spends it.

In your sentence, no emphasis is needed, so leaving out yo is completely normal.

In this sentence, guardar means something like:

• to put away
• to keep
• to store

So guardo el resto del dinero en la cartera suggests physically putting the remaining money into the wallet.

It does not mean to save money in the financial sense as clearly as English save can. Spanish often uses:

• ahorrar dinero = to save money financially

So here guardar is more about putting something somewhere safely.

El resto del dinero means the rest of the money or the remaining money.

Breakdown:

• el resto = the rest / the remainder
• del dinero = of the money

So the phrase refers to whatever money is left after paying the bill.

A useful distinction:

• el resto del dinero = the money that remains
• el cambio = the change you get back after paying

So this sentence is about the remaining money you still have, not necessarily the coins or notes handed back by the cashier.

Because de + el contracts to del in Spanish.

So:

• de el dinero → del dinero

This is a standard rule.

The two main mandatory contractions are:

• a + el = al
• de + el = del

So el resto del dinero is the correct form.

Spanish uses definite articles el / la / los / las more often than English does.

In this sentence:

• la cuenta = the specific bill being paid
• el resto del dinero = the rest of the money already being talked about
• la cartera = the wallet, often understood as the speaker’s wallet

English sometimes drops articles where Spanish keeps them, but in Spanish these articles sound natural and expected.

Especially with a phrase like el resto de..., the article is very common:

• el resto del pan
• el resto del tiempo
• el resto del dinero

In Spain, la cartera commonly means wallet.

That makes this sentence very natural for Peninsular Spanish.

A regional note:

• In Spain, cartera often = wallet
• In many parts of Latin America, cartera can mean purse or handbag

So if you are specifically learning Spanish from Spain, reading cartera as wallet is the right choice here.

Because en marks the place where the money ends up or is kept.

• guardar algo en... = to put/keep something in...

So:

• guardar el dinero en la cartera = put/keep the money in the wallet

Using a would not sound right with guardar in this structure.

Spanish often uses en with containers or locations:

• en la bolsa
• en el cajón
• en la cartera

The original word order is very natural:

• Después de pagar la cuenta, guardo el resto del dinero en la cartera.

But Spanish does allow some flexibility. For example:

• Guardo el resto del dinero en la cartera después de pagar la cuenta.

That is also grammatical, though it puts the after paying the bill idea at the end.

The original version sounds especially natural because it starts with the time/action background first, then gives the main action.

So the order is not completely fixed, but the sentence as given is a very normal and smooth way to say it.

The comma separates the introductory phrase from the main clause:

• Después de pagar la cuenta, = introductory time phrase
• guardo el resto del dinero en la cartera. = main clause

This comma is very natural in Spanish and helps readability.

You may sometimes see short introductory phrases without a comma, but in a sentence like this, using the comma is standard and clear.