Meaning: I felt very happy because of the beauty of nature.
Choice of Words: "Nature" refers to the natural world and its features, and "beauty" is a quality that gives pleasure to the senses or the mind. "Filled" means to make something full, and "heart" is the center of emotions and feelings. "Joy" is a feeling of great pleasure and happiness. The sentence describes the positive emotions experienced by someone when surrounded by the beauty of nature.