The day is almost over. We couldn’t do anything today because of this stupid traffic jam.
A bitter stagnate is when you're stagnated in traffic. It feels bitter, doesn't it? Why can't people drive faster? Why are people looking at the accident instead of driving? I'm so bitter about it! That's why this word is traffic jam and traffic congestion.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.