But in English, "Raj sings song" is not a correct sentence, you must add an article, a/an/the. Articles don't exist in Hindi, so this is the closest translation.
Is गीत/गीता (geet/geeta) also an acceptable way to say "song"? I've heard this word mostly in Sanskrit sources (Bhagavad-Gita, Gita-Govinda, etc.), but I'm not sure if it's used in modern Hindi.