when is it celebrated or observed

It’s not clear what “it” refers to, so I can’t say when it is celebrated or observed.

To give a correct answer, I’d need the name of the specific holiday, observance, or event you’re asking about (for example, “Memorial Day,” “Eid al‑Fitr,” or “World Environment Day”).

Please reply with the exact name of the day or event, and if possible the country or tradition (e.g., US federal holiday, Christian feast, UN day), and I’ll tell you when it is celebrated or observed and how that typically works.

Information gathered from public forums or data available on the internet and portrayed here.