By The End Of The Year
Before The End Of This Year, Within The Year
noun
Inside the year means by the end of the year. In other words, before the end of this year, or within the year.
ねんない
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.
年内には、かんせいするはずです。
It should be complete within the year.
年内にフォロワー10万人目ざします。
I'm aiming to reach 100,000 followers by the end of this year.
この暗殺は、年内に遂行されなくてはならない。
The assassination must be carried out before the year is over.