In the following lines taken from Sir Philip Sidney's "Defense of Poesy" (1595), he is discussing the current state of affairs in poetry and the writing of poetry. In (a), "our tragedies and comedies not without cause cried out against, observing rules neither of honest civility nor skillful poetry," Sidney acknowledges the complaints of those in his time against what tragedies and comedies have become. They do not adhere to "honest civility" or "skillful poetry." In short, they are not well-written, not poetic. In addition, they are not honest. They do not say anything; they are faulty in that they are not true to place and time, both necessities from Sidney's perspective. He discusses this later in this paragraph.
The second statement, (b), refers to Aristotle's theory of rhetoric, specifically to the unity of time and unity of place. Aristotle theorizes that a proper tragedy must possess a unity of time, that is, a short amount of time which encompasses all of the action in the play - usually no more than 24 hours. At the same time, a tragedy must have a unity of place. In other words, it must be consistent in terms of its setting. It should only have one (perhaps two) settings for the entire play. The goal of this is to avoid confusion and allow for the action to be easily understood by the audience. Sidney, writing in the sixteenth century, still adhered to this view of tragedy, as did many other writers well into the next century.
In the final statement, Sidney indicates that a tragedy is not beholden to the historical record for its content. A tragedy can manipulate the historical narrative and invent events to aid in the telling of the tragedy. Sidney warns that the two should not be confused.