Oh I see! I’ll try explain :)
In the first sentence ‘football’ is not a count noun because it refers to the general idea of something. (A count noun needs an article)
In the second sentence, I think ‘orientation week’ is an abstract noun.
‘Stuff’ is a general word. Words like ‘stuff’ ‘things’ ‘anyone’ ‘nothing’ that are non-specific nouns don’t need an article.
In this sentence ‘coffee’ is a noun that is not a count noun because it refers to a general drink. ‘I drink a cup of coffee’ because it is a specific drink (you are looking at a specific cup) but ‘I drink coffee’ because you are talking about a general type of drink.
Does that make sense ?