The end of the year; often refers to year-end activities and preparations. Can also be used adverbially to mean 'at year-end'.
年末は大掃除をして一年の汚れを落とす。
At year-end we do a big cleaning to remove the year's dirt.
年末のセールで家具を買い替えた。
I replaced my furniture during the year-end sale.
会社は年末に納会を開き、みんなで集まる。
The company holds an end-of-year gathering and everyone gets together.