This is a fairly broad question, which is why it is essential for you to take notes on the text in question and identify a few formal features that you can analyze in your response. There are a number of possible components that you could include. For example, how does the text's syntax affect its meaning? Are the sentences short and curt? Or are they long and with many subordinate clauses? Consider how these syntactical features inform the tone of the piece. Another element you could analyze are the lexical choices. Are the words simple or informal? Or are they academic? Do the words have positive or negative connotations? What do these lexical choices tell us about the text's intended audience? These are just a few features that you could identify and analyze in your response.