It is an adverb that means "for a while". It is used to describe a short time.
"当分" is similar to "しばらく", but "当分" is only used when describing a short period of time in the future.
I haven't used Japanese language in a long time, but I'll take the JLPT exam in December. I need to focus on studying for a while.
しばらく日本語を使っていないけど、12月にJLPT試験を受けるつもりだ。当分(orしばらく)勉強に集中しなきゃ。
しばらく日本語を使っていないけど、12月にJLPT試験を受けるつもりだ。当分(orしばらく)勉強に集中しなきゃ。
Ken and Leo are catching up.
- Ken: I'm so busy that I can't take days off for the time being.
忙しくて、当分(orしばらく)休みは取れない。 - Leo: I see. I'm also busy, but I'll take a vacation after this week, I expect that things will settle down by then.
そっか。俺も忙しいけど、来週には落ち着きそうだから、休暇を取るよ。 - Ken: Do you have any plans for the vacation?
何か予定はあるの？ - Leo: I haven't seen my parents for a while so I'd like to visit them.
しばらく両親に会っていないから、実家に行こうと思って。
Meg picked up the phone from Amy's client.
- Client: I'd like to speak with Amy.
エイミさんをお願いします。 - Meg: I'm afraid she is not at her desk at the moment. Should I have her call you back?
あいにく只今席を外しておりますので、折り返し電話させましょうか？ - Client: No, thank you. I'm going to a meeting soon. It looks like it'll take some time so I'll call her back later.
いいえ、結構です。これから会議で、しばらく(or当分)かかりそうなので、後ほどかけ直します。