Csu debenture?

Hey guys- was just looking at my portfolio and noticed 2 shares of a debenture?

I found this and I’m not completely sure what it means… at all.

https://www.csisoftware.com/category/press-releases/2023/08/25/constellation-software-inc.-announces-rights-offering

Before I ask chat gpt, can anyone explain what my options are for this and why there is an expiry date and what does the expiry date mean?

Thanks