I would look at other songs. My kids are being tutored in a language and it wouldn't please me to have them taught a song with explicit lyrics and have them explained/interpreted by someone else. As much as I think children need to be taught about sex, I think that is entirely up to the parents as to when and how when we are talking 8 years old. By 8 all of my children understood the basics of human reproduction. We had not yet covered sexual behaviors, which is really what a lot of this covers. That is another level entirely I am just starting to cover with my 10 year old and will have continuing conversations until he is grown I am sure, as I did with the 2 grown kids I have. I read the lyrics to make sure I recall the song & not sure how I'd explain "I want you in my rear window" to anyone of that age and it really can be interpreted one of two ways I can think of and neither is one I am hoping to explain to my kids any time soon.
Why not tell her the lyrics aren't really age appropriate (I tell my kids this) and suggest a different song she might like, like "Paparazzi"? It's also far easier to explain in general as it will make more sense to her level of understanding romance and attraction. Or even one by a different artist. I have an almost 8 yr old that is an advanced reader and has often asked to read books that wouldn't be appropriate. He has no idea what is in it, so he doesn't understand what he is asking about. He doesn't particularly want information right now about sex, so I tell him there is a lot of sex stuff in that one & he drops it. I also tell him if it's got too much scary stuff in it.
If she doesn't understand the language well enough to understand the words on her own, then she has no concept of what she is even asking & asking a question does not mean a child is ready for the answer. It depends on how much of what they are asking they understand. I am all for honest answers, but my 10yr old son overheard a term used by another child & asked me what it meant. It meant anal sex. I told him this because I did think he should know if he is old enough to start hearing people use such a term. He was horrified & not at all grateful to understand, despite asking and thinking he wanted to know. I am not sorry I told him, but I wasn't looking to explain it to him other than it really was the only answer to what he was asking. If instead he wanted me to teach him song lyrics that referenced anal sex, I'd just tell him the lyrics were inappropriate, let's choose a different song.
I homeschool and the style we use is student directed. I believe in that approach overall. I look at what they are interested & excited about and try to work with that. If they fail to get interested or excited about something they need to learn, then I look at ways to show them it can be interesting or exciting. I love that you want her to be enthusiastic about the lessons. I sincerely believe that matters. I also think you can help her make selections that are appropriate and interesting. I don't cover all the things my kids are excited about right away. I steer it in a way that makes sense for content. We will cover it all eventually, but sometimes they are asking something that needs more algebra to cover & they aren't there yet.
And in a comment I know you said she would rather you watch something adult with you versus alone. I would prefer at 8, she not watch it at all. That doesn't mean that I censor my kids from all sex, far from it. I do censor them from the type that is possibly confusing, very casual, etc. The young ones are still too young to understand sexual dynamics. That is a thing that you start to sort out more toward puberty, through puberty, into early adulthood. I do want them to view sex positively. I want them to know it is healthy, it is likely going to be part of their lives in whatever way they determine, that most humans are sexual. None of my message is negative, it's merely catered to understanding level.
I don't know what all her musical tastes are, but where I live, EVERY little girl that age LOVES "Shake it Off" by Taylor Swift and it's an excellent message about keeping your chin up no matter what anyone says about you. https://www.youtube.com/watch?v=DrFZ6fXyia0
There are many great ones, like Because I am a Queen by India Arie https://www.youtube.com/watch?v=_J4zOYEOW5k
Or Katy Perry has a nice one in Roar too for a positive message. https://www.youtube.com/watch?v=C2l4bdAyFUQ
I remembered a few more, so adding them..
Unwritten by Natasha Bedingfield https://www.youtube.com/watch?v=TtGY4G7II6s
Girl on Fire by Alicia Keys https://www.youtube.com/watch?v=e7xsVF_XTEs
How Far I'll Go from Moana and my kids and the kids I babysit all LOVE it right now. https://www.youtube.com/watch?v=i66p0_wZ9F0
They also love "You're Welcome" also from Moana https://www.youtube.com/watch?v=REntT1Amvxc