I would suggest reading the lyrics without the music accompaniment, and work through the song at your own pace. Try practicing one verse at a time, starting slowly, then each time you sing it sing a bit faster until you can sing it close to the original speed. Once you've done that try to find a lyric video (or a video of the song and open another tab with the lyrics) and practice with the music. Listen to the song till you can remember the tune and that's all the advice I could think of, hope this helps!