Grade In School, School Year, Year In School
Your study year is kind of like the years you've studied. Where do you study? School. What is a year of study in a school? It's your school grade.
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.
My brother is a school year ahead of me.
Some friends are from the same grade.
I skipped classes for the whole school year and went to Australia.