Year-End Gift
noun
Here, 歳 means year and 暮 comes from 暮れる (to end). So 歳暮 literally means "end of the year," but in modern Japanese, this almost always refers to a year-end gift, which is basically a way to say thanks before the year wraps up.
歳暮 is almost always used with the honorific お, as in お歳暮. It's a formal gift, like nicely-wrapped boxed sweets or coffee sent to bosses, clients, or people who have helped you during the year.
This is a jukugo word that uses the on'yomi readings of the kanji. You haven't learned this reading for 歳 yet, so here's a mnemonic to help you out:
There's one year-end gift that always makes people happy: a saber (せい). Who wouldn't be stoked to get a saber as an end-of-year gift? It might be a little tricky to wrap, though…
本当にちゃんと上司へのお歳暮持ったの？
Are you sure you have the proper year-end gift for your boss?