Je m’ennuie quand je reste à la maison toute la journée.

Because s’ennuyer is a pronominal (reflexive-like) verb in French. It means to be bored or to get bored.

So the full verb is:

• s’ennuyer = to be bored

When you conjugate it with je, the se changes to me:

• je m’ennuie = I am bored / I get bored

This is different from ennuyer without the pronoun, which usually means to bore someone:

• J’ennuie Paul = I bore Paul
• Je m’ennuie = I am bored

So the m’ is necessary here.

m’ is the shortened form of me.

French short object pronouns often come before the verb:

• me / m’
• te / t’
• se / s’

Because ennuie begins with a vowel sound, me becomes m’:

• je me ennuie → not used
• je m’ennuie → correct

This shortening is called elision.

A rough pronunciation is:

• zhuh mon-nwee

A few helpful points:

• Je sounds like zhuh
• m’ennuie is pronounced smoothly, almost like mon-nwee
• The e in me disappears in writing and speech before a vowel

The ui in ennuie has the usual French sound heard in words like nuit.

Quand means when.

In this sentence, it introduces the situation in which the speaker feels bored:

• Je m’ennuie quand je reste à la maison...
• I get bored / I am bored when I stay at home...

It connects two ideas:

1. Je m’ennuie = I’m bored
2. je reste à la maison toute la journée = I stay at home all day

So quand tells you under what circumstances the boredom happens.

Because French often uses the present tense for general truths, habits, and things that usually happen.

So this sentence does not have to mean only right now. It can mean something like:

• I get bored when I stay home all day
• I’m bored when I stay at home all day

It describes a general pattern or usual experience.

English does something similar:

• I get tired when I work too much.
• I feel bored when I stay home all day.

In French, rester is the normal verb for to stay / remain.

So:

• je reste à la maison = I stay at home

If you used je suis, that would mean I am, not I stay:

• je suis à la maison = I am at home

That describes your location, but not the idea of staying there for a period of time.

So:

• je suis à la maison = I am at home
• je reste à la maison = I stay at home

À la maison is the standard French expression for at home or to/at the house, depending on context.

In this sentence:

• rester à la maison = to stay at home

You usually use à la maison for the idiomatic idea of being/staying at home.

Dans la maison literally means in the house, and it focuses more on the physical inside of the building. It is possible in some contexts, but it is not the normal expression for at home.

Compare:

• Je reste à la maison. = I’m staying home.
• Je suis dans la maison. = I’m inside the house.

Toute la journée means all day or more literally the whole day.

Breakdown:

• toute = whole / all
• la journée = the day, often with emphasis on the span of the day

So:

• toute la journée = all day long / the whole day

This phrase adds duration to the sentence:

• je reste à la maison toute la journée = I stay at home all day

Because journée is a feminine singular noun.

The adjective tout changes to agree with the noun:

• tout
  • masculine singular
• toute
  • feminine singular
• tous
  • masculine plural
• toutes
  • feminine plural

Since journée is feminine singular, you need:

• toute la journée

Examples:

• tout le jour = the whole day
• toute la journée = all day / the whole day
• toute la nuit = all night

This is a very common learner question.

In many cases:

• jour refers to the day as a unit, date, or simple calendar idea
• journée refers more to the day as a span of time, the experience or duration of the day

That is why French often says:

• bonne journée = have a good day
• toute la journée = all day long

In this sentence, journée fits because the speaker is talking about spending the day at home over a period of time.

Yes. In English, both can work depending on context.

• Je m’ennuie can often be translated as I am bored
• In a sentence about a repeated situation, I get bored may sound more natural

So this sentence could be understood as:

• I’m bored when I stay at home all day
• I get bored when I stay at home all day

The French present tense allows that kind of flexibility.

Because toute la journée already expresses that idea.

French often uses this structure to mean throughout the entire day:

• toute la matinée = all morning
• tout l’après-midi = all afternoon
• toute la soirée = all evening
• toute la nuit = all night

So toute la journée naturally covers all day or all day long.

Yes, in a sentence like this, quand can feel like when or whenever, because the statement is general.

• Je m’ennuie quand je reste à la maison toute la journée.

This suggests a repeated truth:

• Whenever I stay home all day, I get bored.

French does not always need a separate word for whenever in these kinds of everyday sentences.

Yes, it is very standard French word order:

• Je m’ennuie = subject + pronoun + verb
• quand je reste à la maison toute la journée = conjunction + subject + verb + place + time expression

A useful thing to notice is that French object/reflexive pronouns usually come before the verb:

• je m’ennuie
• tu t’ennuies
• il s’ennuie

So even though English says I bore myself only in a very different meaning, French naturally says je m’ennuie for I am bored.

Yes, that is possible, but it is slightly different in meaning.

• je reste à la maison = I stay at home
• je suis à la maison = I am at home

Reste emphasizes the idea of remaining or staying home. Suis emphasizes simply being at home.

So:

• Je m’ennuie quand je reste à la maison toute la journée.
  = I get bored when I stay at home all day.

• Je m’ennuie quand je suis à la maison toute la journée.
  = I get bored when I’m at home all day.

Both are understandable; reste is a good choice if the idea is that the person spends the whole day there instead of going out.

Yes, s’ennuyer is a very common everyday verb.

Other possible ways to express a similar idea include:

• Je m’ennuie chez moi toute la journée. = I get bored at home all day.
• Je trouve le temps long quand je reste à la maison toute la journée. = I find the time drags when I stay home all day.
• Je m’ennuie quand je ne sors pas de la journée. = I get bored when I don’t go out all day.

But Je m’ennuie is the most direct and common way to say I’m bored.