Breakdown of Tā de lǐxiǎng shì dāng zuòjiā, suǒyǐ hěn xǐhuan dú xiǎoshuō.
Questions & Answers about Tā de lǐxiǎng shì dāng zuòjiā, suǒyǐ hěn xǐhuan dú xiǎoshuō.
的 marks possession here, so 她的理想 literally means her ideal / her dream.
The pattern is:
Without 的, 她理想 sounds wrong in standard Mandarin; you almost always need 的 between a pronoun and a regular noun like this.
(There are some fixed expressions without 的 like 我妈, 他哥, mostly with close family terms, but 理想 is not one of those.)
理想 means an ideal / aspiration / goal you seriously hope to realize. It often sounds a bit more rational or realistic.
梦想 literally has dream in it and can feel more emotional or romantic, sometimes less realistic.
- 她的理想是当作家 = Her aspiration/goal is to be a writer.
- 她的梦想是当作家 = Her dream is to be a writer (more emotional, story-like).
Both are correct; the nuance is mostly about how “serious vs dreamy” you want to sound.