Price is quoted as a percentage
A price of 100 means the bond trades at its face value ("par"). A price of 97.50 means 97.5% of face value: a 200,000 nominal position would cost 195,000 plus accrued interest. Above 100 the bond trades at a premium, below 100 at a discount.
Current yield
A 5% coupon bond at a price of 95 has a current yield of about 5.26%. This ignores the gain from buying below par and holding to maturity.
Yield to maturity
Yield to maturity (YTM) is the single discount rate that makes the present value of all future coupons and the final repayment equal to today's dirty price. It assumes the bond is held to maturity, every payment is made on time and coupons are reinvested at the same rate. YTM is the standard way to compare bonds with different coupons and maturities.
Why prices and yields move in opposite directions
A bond's coupon is fixed. If market interest rates rise, new bonds offer higher coupons, so existing bonds must fall in price until their yield matches the market. If rates fall, existing bonds with higher coupons become more valuable and their prices rise.
Spread
Eurobond yields are often discussed as a spread over a benchmark: over mid-swaps for euro issues or over US Treasuries for dollar issues. The spread reflects the extra return investors demand for the issuer's credit and liquidity risk.