How to play this song ?

These are single notes, not chords.
Each note must be played individually.

There are different notations, like, A B C , DO RE MI , Sa Re Ga and numeric notation 1 2 3.
Choose one that fits better for you.

You can distinguish the octave by the color of the note and if it is UPPERCASE (high pitch) or lowercase (low pitch). Enjoy

Unconditionally

Katy Perry Pop

"Unconditionally" is a song by Katy Perry, released in 2013. It is in the key of C major. The track was written by Katy Perry, along with Lukasz Gottwald, Max Martin, Bonnie McKee, and Henry Walter. The song is featured on Perry's fourth studio album, "Prism." As for trivia, "Unconditionally" was well received by music critics and reached the top 20 on several music charts worldwide. The melody of the song is catchy and features strong vocals from Perry, accompanied by a melodic pop production.