Порхай (porkhái) is the imperative form of the verb 'to flutter', like a butterfly or a bird. It's a beautiful, poetic word that you won't hear in everyday conversation, making it a unique find.
In the song, JONY sings, "Порхай, ты порхай" (Flutter, you flutter), directly to his love interest. He uses this lovely image to describe her as being light, graceful, and free, encouraging her to be herself within their 'paradise' of a relationship.
JONY puts all his cards on the table in "Мой Рай" (My Paradise), offering a warm pop track about the rush and risk of falling hard for someone. He calls his partner his personal heaven with the line "Помни, что ты мой рай" ("Remember that you are my paradise") and credits her smile with brightening his entire world ("Ты осветила жизнь мою улыбкой" / "You lit up my life with a smile"). He tells her to "Порхай" ("Flutter" or "fly like a butterfly"), but beneath the sweet compliments lies real anxiety. He begs her not to turn into a regret: "Только я прошу, не стань моей ошибкой" ("Only I ask, don't become my mistake").
What makes the track so catchy is that JONY fully knows the danger he is walking into. Other people have already thrown tons of opinions his way ("Говорили мнений море мне про нас" / "They told me a sea of opinions about us"), but he ignores them because she makes him feel alive. He admits that "любовь игра опасная" ("love is a dangerous game"), yet immediately follows it up with the Russian slang word кайф (kayf): "Но в этом и весь кайф" ("But that is the whole thrill"). In Russian, кайф means a state of pure pleasure, bliss, or high excitement. For JONY, the risk of getting burned is part of the fun.