Express
Things that hurry and go faster than the other things are express. This is often used with trains or subways, so look out for it if you're looking to get somewhere in a hurry. Also be careful in case it doesn't stop at your stop, because 急行 trains don't stop at every station (which is what makes them express!).
きゅうこう
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
けいさつは、はんざいげん場へ急行しました。
The police officer hurried to the scene of the crime.
私にやさしくしてくれた人たちに、急行便でお礼の品を送りました。
I sent thank you gifts express to the people who were nice to me.
あーーーしまったーーーー。急行列車が行ってしまった。ってことは私の遅刻も確定だ。コウイチから受ける処罰がすんごく怖いんですけど。
Oh noooooo! The express train left. Now I'm going to be late. I’m really scared of being punished by Koichi.