Quan estava trista, l'àvia em donava una joguina i jo estava més feliç.

Both estava and donava are in the imperfect.

In Catalan, the imperfect is commonly used for:

• ongoing states in the past
• background description
• repeated or habitual actions

That fits this sentence well: it describes a repeated situation in the past. The idea is basically Whenever I was sad, grandma would give me a toy, and I would feel happier.

If you wanted to talk about one single completed event, you would normally use a different past tense, such as: Quan vaig estar trista, l'àvia em va donar una joguina... That would sound more like one specific occasion.

In this sentence, quan can often be understood as whenever, because the imperfect suggests a habitual past situation.

So although the literal word is when, the full sense is closer to: Whenever I was sad, grandma would give me a toy...

Catalan often lets the tense give that repeated meaning, without needing a separate word for whenever.

Yes. Trista is the feminine singular form of trist.

Since the subject is omitted, the adjective helps show who is being described. Here estava trista means the speaker is feminine: I was sad said by a female speaker.

If the speaker were male, it would be: Quan estava trist...

So the ending of the adjective agrees with the understood subject.

Catalan usually uses estar for temporary emotional or physical states, such as being sad, tired, happy, nervous, and so on.

So:

• estava trista = I was sad
• estava més feliç = I was happier / I felt happier

Using ser instead would suggest something more permanent or characteristic. In this sentence, the speaker's sadness and happiness are temporary feelings, so estar is the natural choice.

Because the article la contracts before a vowel and becomes l'.

So:

• la àvia becomes l'àvia

This is very common in Catalan:

• l'amic
• l'escola
• l'àvia

The apostrophe shows that the vowel of the article has been dropped.

In Catalan, family members are often referred to with the definite article when the relationship is already clear from context.

So l'àvia can naturally mean grandma or my grandmother, depending on the situation.

If you want to be explicit, you can also say: la meva àvia = my grandmother

But in everyday Catalan, leaving out the possessive is very common when it is obvious whose family member is meant.

Em means to me.

The verb donar often works with:

• a direct object: the thing being given
• an indirect object: the person receiving it

So in: l'àvia em donava una joguina

• l'àvia = the subject
• em = to me
• una joguina = a toy

Literally, it is something like: Grandma was giving me a toy
or in more natural English here: Grandma would give me a toy

Catalan puts this weak pronoun before a conjugated verb:

• em donava
• em diu
• em va donar

Yes, Catalan often leaves out subject pronouns because the verb ending already shows the subject.

So estava més feliç would already be enough for I was happier.

The pronoun jo is included here for emphasis or contrast. It helps separate the second clause and makes the speaker slightly more explicit:

• ...i jo estava més feliç = ...and I was happier

Without jo, the sentence would still be grammatical and natural: Quan estava trista, l'àvia em donava una joguina i estava més feliç.

Because feliç has the same form for masculine and feminine singular.

So:

• un noi feliç
• una noia feliç

That is why the sentence says més feliç even though the speaker is feminine.

In the plural, the forms do change:

• masculine/mixed plural: feliços
• feminine plural: felices

Més means more, so més feliç means happier.

Catalan usually forms the comparative with: més + adjective

Examples:

• més gran = bigger
• més interessant = more interesting
• més feliç = happier

So instead of changing the adjective itself the way English often does, Catalan typically uses més.

Una joguina means a toy.

The article una is indefinite, so it does not point to one already identified toy. It simply introduces a toy as something grandma would give.

Grammatically, una joguina is the direct object of donava.

If it were a specific toy already known in the conversation, Catalan would more likely use the definite article: la joguina = the toy