There
noun, pronoun, こそあど word
Remember how words beginning with そ are either close to the person you're talking to, or fairly close to both of you? And how words ending in こ refer to places? This one's no exception. そこ means there.
そこで先生に会ったよ。
I met my teacher there.
おやつなら、そこにあるよ。
If you're looking for snacks, they're there.
そこまで言わなくてもいいじゃない!
You don't have to say so much!