What does 21:00 mean? Understanding 9:00 pm

"It's nine o'clock in the evening. The day has slowly transitioned into night, and the ambient light begins to dwindle, giving way to the gentle glow of artificial illumination. At this hour, many people are winding down after a long day, seeking relaxation and tranquility. The streets are quieter now, with the hustle and bustle of daytime activities fading into the background. In homes, families may be gathering for dinner, engaging in conversations about their day, or perhaps enjoying some leisure time together. The night is still young, yet there is a sense of calmness and serenity as the world settles into the peaceful rhythm of the evening."