Would you mind if I asked you to do some errands?
Sorry! I have to take care of something and I have to cancel my lesson today.
I have an important matter to attend to so I will not be able to work tomorrow.
A task action is something you have to do (because 事 is all about actions). What's another way to say "an action that is a task," though? I would say errand or even business.
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.