According to its prospectus, UOB's new bonds are AT1s, which are the most subordinated tranche of bank bonds. UOB's AT1s are perpetual in nature (and thus have no firm maturity date), and have loss absorption features which may entail a write-down of principal if MAS decides that UOB is no longer viable (or requires a public sector bail-out).
In this sense, it is not a coco bond and there is no conversion to ordinary shares should the bank no longer become viable. There will probably be a haircut to the principal if MAS so decides.