https://en.wikipedia.org/wiki/Barracuda_(song)

Ann Wilson revealed in interviews that the song was about Heart's anger towards Mushroom Records, who as a publicity stunt released a made-up story of an incestuous affair involving Ann and her sister Nancy Wilson. The song particularly focuses on Ann's rage towards a male radio promoter who came up to her after a concert asking how her "lover" was. She initially thought he was talking about her boyfriend, band manager Michael Fisher. After he revealed he was talking about her sister Nancy, Ann became outraged, went back to her hotel room, and wrote the original lyrics of the song.[3]

Producer Mike Flicker added that Mushroom Records was so obtuse in the contract negotiations that Heart decided to discard the album they were working on, Magazine—which the label still released in an unfinished form—and instead sign with the newly formed Portrait Records to make another record, Little Queen. As Flicker put it, "'Barracuda' was created conceptually out of a lot of this record business bullshit. Barracuda could be anyone from the local promotion man to the president of a record company. That is the barracuda. It was born out of that whole experience."[4]
Music

In a March 2019 interview with Gear Factor, Nancy Wilson revealed that the guitar riff for "Barracuda" was inspired by the riff from Nazareth's cover of the Joni Mitchell song "This Flight Tonight". Wilson said: We've been opening for a band called Nazareth in Europe and also for Queen. And Nazareth had a hit with a Joni Mitchell song that they covered [in 1973] called "This Flight Tonight" that had kind of that riff.

So we kind of borrowed that. And we made it into "Barracuda". And we saw the guys from Nazareth later and they were pissed. "You took our riff!".

But that's kind of what everybody—you borrow from what you love and then you make it your own. It's one of those sounds too, it's one of those guitar tones that I'm still trying to figure out what we did. [Laughs] It's hard to re-create.[5]