Q. What do you mean by yield curve?
Yield curve is a graph of interest rates of different maturity (recalculated to yearly rates) at a specific point in time. It's common for the yield curve to slope upwards (interest rates with longer maturity are normally higher than those with a shorter maturity). Reason for this is that there is a higher demand for loans with longer maturity owing to the decreased uncertainty. Many borrowers are prepared to pay a premium to avoid fluctuations in the interest rates.
As discussed above, if market expects higher interest rates then slope of the yield curve would increase. Though not very common, slope may be negative if market expects the interest rates to fall more than premium on longer rates.