Soon
Before Long, Shortly
adverb
The もなく part is like saying "there isn't even." So, when "there isn't even an interval of time," things will happen soon or before long.
You'll probably hear this the most in train announcements letting you know your train will shortly be arriving in Tokyo or wherever.
まもなく
The reading for this one is weird, though. It's a second kun'yomi reading (there is also あいだ), read as ま. So what is happening soon? Your Ma is going to be here before long. You better hurry and prepare, because your room looks terrible...
"間もなく, your mom is about to show up!"
間もなくかいえんです！
The curtain rises soon.
大学いん研究生のしょう学金についてのへんじが、間もなく来るはずです。
I'll probably get a reply regarding the postgraduate research scholarship before long.
もう間もなく夕飯が出来上がる頃ですが、クッキーを食べる手が止まりません。
Supper will be ready really soon but I still can’t stop eating these cookies.