这是非常有意义的一件事，如何用英语表达，在线等

This is a quite significant issue/event.
issue/event指大的，重要的事情

This is a matter worth a lot.

This is a very significative thing.

This is a very meaningful matter .

This is a mean thing.
What a mean thing.

书面化点：This is a significant event;/This is an event of great significance.
口语化点：This is a meaningful thing.