The word "gleam" has multiple meanings, depending on its context.
1) It can refer to a bright or shiny light that reflects off an object, often seen in the eyes of animals such as dogs or cats. For example, "I saw a gleam in his eye."
2) In a more figurative sense, it means a sparkle or radiance, usually associated with happiness or excitement. An example would be: "She had a gleam in her eye when she talked about the new project at work."
3) It can also mean a brief moment of intense emotion or enthusiasm. For instance, "There was a gleam of hope in his voice as he spoke about the future."