Just wondering how i know that its "a newspaper and not " the newspaper" in this context?
Irish doesn't have an indefinite article, so if it's the noun by itself, it's indefinite. an is the definite article.
"Tá" means "Is", but it has a different function than the word "Is". It can also be used as a substitute for the word "Yes", as there is none in Irish. "Tá" is used to describe something directly (I.e.: "Tá fear gorm" meaning "The man is blue"). "Is" is used to refer to something's properties in a less direct manner. (I.e.: "Is é fear gorm" meaning "He is a blue man"). Note that I'm extremely rusty, and I may not be explaining it perfectly or completely accurately, but I still remember the general idea. There are other rules surrounding the two versions of "Is", and I suggest you ask some of the many experienced learners here. :3