Translation:Raj sells apples.
Raj sells an apple. Is it correct?
A more apt Hindi translation for your sentence would be: राज एक सेब बेचता है।
If it's apples and not apple, shouldn't it be हैं?
Here, 'है' refers to the subject 'Raj' (राज) and not to the object 'apples' (सेब). Since Raj is singular, usage of 'है' is apt here.