Quand le grille-pain ne fonctionne pas, nous mangeons les tartines froides avec de la confiture.

Quand can mean when, but in a sentence like this it often has the sense of whenever or when(ever).

Here, Quand le grille-pain ne fonctionne pas, nous mangeons... means something like:

• When the toaster doesn’t work, we eat...
• or more naturally in English, Whenever the toaster doesn’t work, we eat...

French often uses the simple present in both parts of this kind of sentence.

In French, nouns usually need an article much more often than in English. So instead of saying simply toaster, French normally says the toaster: le grille-pain.

That does not necessarily mean a very specific toaster is being emphasized. It is just the normal French way to talk about a noun in a sentence.

Grille-pain literally means something like bread-griller.

It comes from:

• griller = to grill / toast
• pain = bread

French often forms compound nouns this way. Even though it looks unusual to an English speaker, le grille-pain is simply the normal word for toaster.

This is the standard French way to make a verb negative.

• fonctionne = works / functions
• ne fonctionne pas = does not work

So:

• Le grille-pain fonctionne. = The toaster works.
• Le grille-pain ne fonctionne pas. = The toaster does not work.

In careful written French, both ne and pas are used. In everyday spoken French, people often drop ne, but you should keep it in normal writing.

Yes, marche is also very common.

Both can mean works in this context:

• Le grille-pain ne fonctionne pas
• Le grille-pain ne marche pas

Fonctionner sounds a little more formal or technical. Marcher is very common in everyday speech for machines and devices.

So this sentence is completely natural, but ne marche pas would also be very common.

Nous mangeons is simply the present tense of manger for nous:

• je mange
• tu manges
• il/elle mange
• nous mangeons
• vous mangez
• ils/elles mangent

There is no negation here because the second part is positive: we eat the toast cold with jam.

Also, notice the spelling mangeons with eons. The extra e is there to keep the soft g sound.

Compare:

• nous mangeons → soft g sound
• without the e, it would look like it should sound different

Une tartine usually means a slice of bread with something spread on it, or sometimes just a slice of bread served for eating, especially in contexts like breakfast.

In this sentence, les tartines froides avec de la confiture suggests slices of bread eaten cold with jam.

A native English speaker may want to translate it as toast, but tartine is not always exactly the same as English toast. It depends on context. Here, because the toaster is not working, the idea is that they eat the bread cold instead of toasted.

Les means the and des means some.

French often uses the definite article where English might sound more natural with no article or with a possessive. Here, les tartines refers to the slices of bread involved in the situation—the ones they are eating.

So nous mangeons les tartines froides is natural French for this context.

If you said nous mangeons des tartines froides, that would sound more like we eat some cold slices of bread, introducing them less specifically.

In French, most adjectives come after the noun.

So:

• des tartines froides = cold slices of bread
• literally: slices of bread cold

That is normal French word order. A small group of common adjectives often comes before the noun, but froid is not one of them in this use.

Because tartines is:

• feminine
• plural

French adjectives usually agree with the noun they describe.

The basic adjective is froid. Its forms are:

• masculine singular: froid
• feminine singular: froide
• masculine plural: froids
• feminine plural: froides

Since tartines is feminine plural, the adjective must be froides.

French normally needs an article before a noun like confiture in this kind of sentence.

De la confiture is the partitive form, used for an unspecified amount of something uncountable:

• de la confiture = some jam

So:

• avec de la confiture = with jam / with some jam

Saying avec confiture would sound incomplete or unnatural in standard French.

Because confiture is a feminine singular noun, and in an affirmative sentence French uses the partitive article:

• masculine singular: du
• feminine singular: de la
• before vowel or mute h: de l'
• plural: des

So:

• du pain
• de la confiture
• de l'eau
• des légumes

You often get plain de instead of du / de la / des after negation, but that is not happening here.

The comma separates the when-clause from the main clause.

• Quand le grille-pain ne fonctionne pas, = When the toaster doesn’t work,
• nous mangeons les tartines froides... = we eat the bread cold...

This is very similar to English, where you often use a comma after an introductory when clause.

Yes, that would also be grammatical.

You can say:

• Quand le grille-pain ne fonctionne pas, nous mangeons les tartines froides avec de la confiture.
• Nous mangeons les tartines froides avec de la confiture quand le grille-pain ne fonctionne pas.

The first version puts more emphasis on the condition or situation first. The second begins with the main action.

Both are correct.

French often uses the present tense to express habitual actions or general truths.

So this sentence means something like:

• Whenever the toaster doesn’t work, we eat the bread cold with jam.

This is not necessarily happening right now. It can describe a repeated habit or what usually happens in that situation.

English does the same thing:

• When the toaster doesn’t work, we eat...

It is perfectly correct, and it is standard written French.

In everyday spoken French, many speakers use on instead of nous:

• Quand le grille-pain ne fonctionne pas, on mange les tartines froides avec de la confiture.

That sounds more conversational. But nous mangeons is absolutely normal and important to know, especially in writing and more formal speech.