Your app's name is an important part of your app's brand, but is also displayed throughout the system and should fit in.

Branding vs. Describing

In many cases, you want to carry a distinct brand to a user's desktop, and your app's name is likely the first thing a user will hear. It should be distinct and short (three syllables or less is typically good), and not contain excess words. For example, the elementary address book app is called "Dexter;" it's two syllables, unique, and contains no extra words.

For specifics related to the .desktop file itself, please refer to App Launchers.