"A meal" एक भोजन
'A' is used because an article is needed in English. When it comes to Hindi, simply "भोजन" is enough. "एक भोजन" is a word to word translation that does not represent the natural form of construction in Hindi.
खाना cannot be used here?
'Meal' is right word
A meal is wrong word. here will be MEAL
A meal के आगे A क्यों लगाया गया है
A meal why