1Another place; somewhere else — a location other than the one currently being referred to. Used as a place noun in patterns like ほかで (somewhere else), ほかへ (to somewhere else), ほかに (anywhere else).
ここではゆっくり話せないから、ほかで会おう。
We can't talk properly here, so let's meet somewhere else.
この本、近所では売っていなかったので、他で探してみる。
I couldn't find this book locally, so I'll look for it somewhere else.
この件は他の部署で扱っているので、そちらに問い合わせてください。
This matter is handled by another department, so please direct your inquiry there.
2Another person, thing, or one of the rest — anyone or anything other than the one(s) just mentioned. Common in attributive form 他の〜 / ほかの〜. The most basic sense, used heavily in both speech and writing.
自分のことだけでなく、他の人の気持ちも考えたほうがいい。
You should think about other people's feelings, not just your own.
他に何か質問はありますか。
Are there any other questions?
この色が気に入らないなら、ほかのもお見せしましょうか。
If you don't like this color, shall I show you others?
参加したのは山田さんと佐藤さん、ほかに三人いた。
Yamada and Sato joined, and there were three others as well.
3In the fixed pattern 思いのほか, meaning "more than expected" or "unexpectedly so." Usually written in kana (ほか); when given a kanji, 外 is the form sometimes used. Close in meaning to 思ったより and 案外.
今日のテストは思いのほか難しかった。
Today's test was harder than I expected.
初めて行った店だったが、料理は思いのほかおいしかった。
It was my first time at the restaurant, but the food was much better than I'd expected.
工事は思いのほか早く終わって、来週には引っ越せそうだ。
The construction finished sooner than expected, so we should be able to move in next week.
4In negative or no-choice constructions like 〜のほかに〜ない ("no one/nothing other than 〜") and 〜するほか（は）ない ("have no choice but to 〜"), expressing exclusivity or the lack of any alternative. A key N3 grammar pattern.
この問題を解ける人は、君のほかにいない。
There is no one but you who can solve this problem.
終電を逃したので、歩いて帰るほかなかった。
I missed the last train, so I had no choice but to walk home.
事実を知っているのは本人のほかにいない。
No one but the person himself knows the truth.
ここまで来たら、最後までやり遂げるほかない。
Now that we've come this far, there's nothing for it but to see it through.
5In the pattern 〜のほか（に）, meaning "in addition to 〜", "besides 〜", or "as well as 〜". Used to add a further item or fact to what has already been mentioned.
彼女は日本語のほかに、英語と中国語も話せる。
Besides Japanese, she can speak English and Chinese as well.
入場料のほかに、駐車場代も別途必要です。
In addition to the admission fee, there is a separate parking charge.
仕事のほかに、何か趣味はありますか。
Apart from work, do you have any hobbies?
彼は学業のほかにサッカー部でも活躍している。
Besides his studies, he is also active in the soccer club.