Billie Eilish shows off her linguistic skills by singing in Spanish on her new duet with fellow pop star Rosalia.

The artists teased the release of Lo Vas A Olvidar (You Will Forget Her) on Tuesday, and on Thursday, fans were finally able to check out the tune, almost two years after the singers first connected in the recording studio.

The sombre track features Billie and Rosalia trading lines in Spanish and harmonising together, before the Bad Guy hitmaker closes the song in English, asking, “You say it to me like it’s something I have any choice in / If I wasn’t important, then why would you waste all your poison?”

Billie has revealed she enlisted the help of her entire family when she wrote the final words for the track. Her brother Finneas O'Connell, who is her primary co-writer, as well as her mother and father and Finneas' girlfriend Claudia all contributed ideas for the line.

“We all came down to the studio, and we listened, and me and Finneas were like, ‘Should we just write this line right now?'” she said while speaking to Zane Lowe on Apple Music.

“We both, all of us, including my dad and my mom, they were like, ‘What if it was like….’ We were all giving ideas. So technically they should have a writing credit, because we all wrote that line right at the end.”

The accompanying dream-like music video, filmed by top director Nabil, was also released on Thursday.

Lo Vas A Olvidar is set to feature in an upcoming episode of Zendaya's hit TV series Euphoria, which premieres this weekend.