The core idea
Bond yields often fall when investors expect lower policy rates, weaker economic growth, softer inflation or greater demand for safe and liquid assets. Falling yields can also reflect central-bank purchases or declining term and credit premia.
What is happening underneath
During a growth scare, investors may buy government bonds while simultaneously pricing future monetary easing. Higher bond prices then correspond to lower yields.
How investors should read it
A yield decline is therefore not automatically bullish or bearish for the economy; its meaning depends on the driver.
The same market move can carry different information depending on which maturity, issuer and risk premium is changing. Read the question together with the underlying concepts rather than treating one price move as a universal signal.