This explanation about grammar particles omits some details.
I learned how to use postpositions at school today, but I'm still so confused.
In Japanese grammar, one of the most difficult things to master is particles.
A part of speech that's just meant to help your grammar out are the little things. They tie grammar and words together, and that's about it. These are grammar particles or just plain old particles.
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.