It can mean either one, depending on context.
Afrikaans often uses the simple present for both:
If you want to make the ongoing action very clear, Afrikaans can use a longer form such as Sy is besig om poësie te lees, but the simple sentence Sy lees poësie is very common.
Because poësie is being used in a general, uncountable sense, like English poetry.
Compare:
So in your sentence, poësie means poetry in general, and no article is needed.
Sy lees nie poësie nie.
Afrikaans usually uses a double nie in standard negation:
That double negative pattern is a very important feature of Afrikaans.
In a main clause, Afrikaans usually keeps the verb in the second position.
So if you move another element to the front, the verb still comes next:
Notice that when Vandag moves to the front, lees still stays second, and sy moves after the verb. This is a very important Afrikaans word-order rule.