Noun markers are “A” “An” and “The”.
Noun markers are also called article adjectives.
Noun markers/article adjectives answer the questions “who?” and “what?”
Examples of correct noun markers for one thing: An orange, a song, a book, and an eraser are all correct noun markers.
Examples of correct noun markers for more than one thing: The birds, the children, and the pens.
Often noun markers come before nouns.