Learn Spanish (Latin America): A ellas les da envidia tu nueva casa.

In this Spanish structure, the thing causing the emotion is actually the subject of the sentence. The subject here is tu nueva casa (your new house), which is singular, so we use the singular verb da. Literally, the sentence is saying "Your new house gives envy to them."

Why do we have both A ellas and les when they refer to the same people?

Spanish requires the indirect object pronoun (les) in sentences using verbs of emotion like dar, even when the people receiving the action are explicitly named. The pronoun les is mandatory for the grammar to work, while the phrase A ellas is optional and used here to add emphasis or clarify exactly who "they" are.

Why does this sentence use envidia (envy) as a noun instead of an adjective for "envious"?

When talking about emotional reactions, Spanish frequently uses the verb dar (to give) paired with a noun. Instead of describing how a person is (envious), Spanish describes what the situation gives them (envidia). You will see this same pattern with other emotions, like dar miedo (to cause fear) or dar vergüenza (to cause embarrassment).

Can I change the word order and put tu nueva casa at the beginning of the sentence?