1Now; the present moment, or the time at which one is speaking. Read いま and used as either a noun or an adverb. Depending on context it can also cover the immediate past ('just now', 'a moment ago') or the immediate future ('right now', 'soon'). Read こん, the same kanji 今 functions as a prefix in compounds like 今回 or 今夜.
今すぐ出発しないと間に合わない。
If we don't leave right now we won't make it in time.
今は手が離せないので、後でかけ直します。
I can't get free right now — I'll call you back later.
彼は今帰宅したばかりで、まだ食事をしていない。
He just got home and hasn't eaten yet.
今のところ、これといった問題は見つかっていない。
As of now, no notable problems have been found.
今を生きることが何より大切だ。
Living in the present is what matters most.
2Another; one more — an older usage surviving in fixed phrases like 今一度 (いまいちど, 'once more') and 今一つ (いまひとつ, 'one more'). In modern speech 今一つ has shifted to a negative nuance meaning 'not quite enough / a bit lacking', as in 今ひとつ気に入らない ('not quite to my liking').
申し訳ありませんが、今一度ご確認いただけますでしょうか。
I'm sorry, but could you check it one more time?
新作の映画は評判ほどではなく、今一つだった。
The new film didn't live up to its reputation — it was a bit underwhelming.