<p>Apparently reading the editorials in the newspaper ups your vocab and reading comprehension,you could try that. "Time is on [someone's] side" means that things will work out with time, I don't know any other way to explain it. Yeah, our American sayings are weird and useless for the most part.</p>
<p>I think "time is on your side" means you have plenty of time for something. Like, "I know you have to memorize a lot of vocab words, but time is on your side."</p>
<p>READ THE ECONOMIST (not Time/Newsweek). The articles are of much higher quality. Also, it's a little bit more balanced from an international perspective. </p>
<p>Time is on your side=time is your friend=you've got lots of time to accomplish what you need to. E.g. in studying for the CR section of the October test, time is on your side since it's only June now :)</p>
<p>A cheaper/easier option to read blogs, particularly if you're into politics.</p>