I already responded to your other question on the same concept but a further example might help. In addition to indirectly describing the character’s mood through thoughts or behaviors, you can also create an environment/setting that triggers the chosen emotion (anger) or communicates it to the audience (such as a gray, rainy sky when a character is sad).
“The hot sun shone through the thin windshield, further reddening the flushed cheeks of the already flustered driver. She gripped the steering wheel with heavy knuckles and bared her teeth to prevent further profanity from escaping her mouth. Her labored breathes pushed her exasperation throughout the cab of the car while she tapped her left foot into the floor-mats. The traffic lurched with her shaking knee and forced her into tight lanes of vehicles preventing her from reaching the grocery store. Her horn blared loudly.”