This sentence is an example of how Japanese is often spoken.
As you see, the subject is usually left out. 「この後、何をしますか。」 literally means “After this, what will (you) do?” — the “you” is understood from context.
    
    What you see
    
      You’ll notice a mix of kanji and hiragana. The kanji are
      後 (“afterward”) and
      何 (“what”). The rest is written in
      hiragana to form the sentence.
    
    
    … Tap to expand