Mi hermano es muy pesado cuando bromea todo el día.

Because pesado has both a literal and a figurative meaning.

• Literal: heavy
• Figurative (very common in Spain): annoying, tiresome, a pain

So in this sentence, Mi hermano es muy pesado does not mean that your brother is physically heavy. It means he is really annoying / tiresome, especially because of the behavior described after it.

This figurative use is extremely common in everyday Spanish in Spain.

Both can exist, but they suggest slightly different things.

• Es muy pesado = this is presented more as part of his behavior or character in that situation; it sounds more general or typical.
• Está muy pesado = he is being especially annoying right now or in this temporary moment.

In your sentence, es muy pesado cuando bromea todo el día sounds like a habitual pattern: whenever he spends all day joking around, he becomes very annoying.

A learner-friendly way to think about it:

• ser = more general description / recurring trait
• estar = more temporary state / how someone is acting at the moment

That said, in real conversation, natives may use either depending on what they want to emphasize.

It means when he jokes all day or when he keeps joking all day.

Here, cuando introduces a clause that describes the situation in which the brother is annoying.

Structure:

• cuando = when
• bromea = he jokes / he is joking
• todo el día = all day

So the full idea is:

• My brother is very annoying when he jokes all day.

This is a very normal way in Spanish to describe a repeated or typical situation.

Because the sentence is talking about a habitual or general situation, not one single completed event.

Spanish often uses the present tense for things that happen regularly or are generally true:

• Mi hermano es muy pesado cuando bromea todo el día.
• My brother is very annoying when he jokes all day.

This is similar to English, where we also use the present for repeated behavior.

Bromea is the third person singular present of bromear:

• yo bromeo
• tú bromeas
• él/ella bromea

Yes, but it changes the feel slightly.

• cuando bromea todo el día = more neutral, general, habitual
• cuando está bromeando todo el día = emphasizes the ongoing action more strongly, like when he’s spending all day joking around

The original version is simpler and very natural. The estar + gerundio version is also possible, but it sounds a bit more focused on the action as it unfolds.

So:

• bromea = he jokes / he jokes around
• está bromeando = he is joking / he is in the middle of joking

Because Spanish usually does not need subject pronouns when the verb ending already shows who the subject is.

In bromea, the ending -a tells us it is he/she/you formal.

So cuando bromea already means:

• when he jokes
• or when she jokes
• or when you joke (formal)

In this sentence, the subject is clearly mi hermano, so adding él would usually be unnecessary.

Todo el día means all day or the whole day.

It is a very common time expression in Spanish:

• trabaja todo el día = he works all day
• llueve todo el día = it rains all day
• bromea todo el día = he jokes all day

It suggests the action lasts for a long time, which helps explain why the brother is described as pesado.

Because they mean different things:

• todo el día = all day
• todos los días = every day

So:

• bromea todo el día = he jokes all day long
• bromea todos los días = he jokes every day

Your sentence is about duration within a day, not about repetition across many days.

The infinitive is bromear, which means to joke.

Bromea is the third person singular present indicative form.

Conjugation of bromear in the present:

• yo bromeo
• tú bromeas
• él/ella/usted bromea
• nosotros/nosotras bromeamos
• vosotros/vosotras bromeáis
• ellos/ellas/ustedes bromean

It is a regular -ear verb.

Not usually. In Spain, pesado is generally an informal, common, fairly mild way to say someone is annoying, boringly persistent, or a bit of a nuisance.

Depending on tone, it can sound:

• playful
• irritated
• critical

But it is usually not extremely offensive. It is much softer than a serious insult.

For example, saying No seas pesado means something like:

• Don’t be annoying
• Stop being a pain

Very common in everyday speech.

Because in Spanish, a possessive adjective like mi normally goes directly before the noun, without an article.

So:

• mi hermano = my brother
• tu casa = your house
• su coche = his/her/your car

You do not normally say el mi hermano in standard modern Spanish.

Yes, especially because of pesado in the sense of annoying. That usage is very common and natural in Spain.

It can also be understood elsewhere, but learners often notice it especially in Peninsular Spanish. In Spain, people frequently say things like:

• Qué pesado eres.
• No seas pesada.
• Es un pesado.

These all mean that someone is being annoying or tiresome.

Yes, exactly. The idea is not that he is funny in a positive way. It suggests that he keeps joking so much that it becomes irritating.

So the feeling is closer to:

• he jokes around too much
• he never stops joking
• after a while it becomes annoying

That is why pesado works so well here: it captures the idea that the behavior goes on too long and becomes tiresome.