It has two meanings. The first meaning is "at/in" and it is used to specify the location, time or situation of something. The second meaning is "regarding" and it is used to describe the subject you are talking about.
It is written language and you may see it often in the news and novels. You can use "で" instead of "において" in everyday conversations.
In my life, the time I spent in Japan is irreplaceable and precious to me.
私の人生において(orで)、日本で過ごした時間はかけがえのない時間だ。
私の人生において(orで)、日本で過ごした時間はかけがえのない時間だ。
Ken is having a job interview.
- Interviewer: The biggest competitor of the TV industry is YouTube. Do you think that we will be able to beat it?
TV業界において、最大のライバルはYouTubeです。我々は勝てると思いますか？ - Ken: I think that the TV industry should find a way to coexist with streaming services, such as Netflix and YouTube.
TV業界はNetflixやYouTubeのような動画配信サービスと共存する道を考えるべきです。 - Interviewer: I see. Do you have any questions about the salary and employee benefits?
なるほど。給与や福利厚生において、何か質問はありますか？ - Ken: I don't have any questions at the moment.
今のところ、ありません。
Ken and Leo are talking about Tokyo Olympics. It will be postponed until next year due to the COVID-19.
- Ken: Do you really think that the Olympics will be held in Tokyo next year?
来年オリンピックは東京で(orにおいて)行われる予定だけど、本当に実施されると思う？ - Leo: I'm not sure about it, but even if they are taking place, the whole event might be smaller.
よく分からないけど、開催されるとしても、規模は縮小されるだろうね。 - Ken: I hope it will happen. I'll be volunteering in the event so I'd like to use my English skills.
やるといいな。ボランティアで(orにおいて)英語力を生かしたいな。