I have read on the internet that a certain ABC university provides an average financial aid of $30,000. So, is this his for the total of the 4 years or is this aid for one year only?
We can’t tell what the context was for an unknown school based on something you read on the internet. Generally though, when you see vague information about the amount of aid a school awards, this average includes federal grants that are only available to US citizens and permanent residents. The average is also probably the average for students who received aid, not for the entire student body. So a school that only gives financial aid to a small number of students could have a misleadingly high average aid amount. Finally, unless what you read said otherwise, the school probably has a different criteria for admitting and awarding aid to international students.
Most universities do not award need based aid to internationals. Some offer merit aid. The wealthy Harvard’s etc. are generous with aid for internationals but the trick is getting accepted first!