"I know north from south" means I know everything or I know a lot of stuff or I have been to Norht and South, so I know a lot (context: people thing about me I do not know anything, but I know north from south.)
Ever since I loved you. "Through the springs and the summers" means all the time or since then up to now or I love you no matter what? Thank you for the answer.
The expression is usually "one doesn't know north from south" and it means they don't know anything. Since the difference between north and south is such a basic and simple fact, the expression implies that if a person doesn't know even this, then they really don't know anything. There are countless variations on this expression, all with a similar structure ("doesn't know X from Y" where X and Y are everyday things that should be clearly distinguishable, even to an uneducated person).
Your second expression (which should probably be a separate question) is unintelligible to me. "Ever since I loved you" is not a complete sentence and it's not clear how "through the springs and summers" is supposed to relate to this.