It depends on whether you are buying or already holding. A bond’s yield is the return an investor can expect from it, and yields move opposite to prices: when yields rise, the market value of existing bonds falls. So high yields are good for new buyers, who lock in more income, but bad for current holders whose bonds lose value if sold early.
A high yield can also be a warning sign. Riskier borrowers must pay more to attract lenders, so an unusually high yield compared with similar bonds often reflects greater default or credit risk. For borrowers such as governments, companies, and home buyers, rising bond yields generally mean higher borrowing costs.
Source: Yield (finance), Wikipedia
Image: 1945 2.5% $500 U.S. Treasury bond coupon by JHerbstman, public domain, via Wikimedia Commons.