When someone is presentable, they're clean and tidy and generally pulled together. They're prepared for interacting with other people. When you first roll out of bed in the morning, you rarely feel very presentable.
Before you head off to school or work, you'll want to glance in the mirror to make sure you're somewhat presentable. For some of us, this means a shower, a hair dryer, makeup, and carefully chosen clothing, while for others it means trading pajamas for a comfortable pair of jeans. Since the early 1800s, presentable has meant "appearing suitable" or "fit to be seen." Before that, it had a purely legal meaning, "liable to be charged with wrongdoing."