Over There, Opposite Side, Other Side, Far Away
noun
You know that 向 means yonder. So, think of a "yonder こういち." All you know is that he's over there on the other side / opposite side of where you are. Basically, he's just pretty far away, wherever he is.
むこう
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: Standing with こういち is a cow. It is saying moo (む). Weird, now こういち is saying it too. Also, if you know the reading of 向く you should be able to read this one as well.
山の向こうには何が見えますか？
What can you see on the other side of the mountains?
道の向こうのベーカリーでパンを二斤買いましょう。
Let's buy two loaves of bread at the bakery on the other side of the road.
海外に行くと、毎回向こうの文化にインスパイアされるんですよ。
When I go abroad, I'm inspired by the culture over there every time.