Changes in the yield curve have been in the news when an “inversion” occurs; when shorter term bonds have yields higher than longer term bonds. Without getting into the math, yield curve inversions tend to precede recessions since Fed tightening at the short end (higher rates) reduces demand for credit thus causing lower rates at the longer end.
Another perspective on yield curve inversions has to do with forward rate math; the idea that a string of interest rates indicates what rates in the future will be. Without getting into the math, forward rates are not very predictive, except over very, very short time horizons. Though I respect the bond managers at PIMCO, I think they have it wrong here during this Bloomberg interview; they might be right, but I would not bet on it!
https://www.bloomberg.com/news/articles/2019-01-02/key-fed-yield-gauge-points-to-rate-cuts-for-first-time-since-08