fixed typo in putting-it-all-together section, line 857

Author: spaceC00kie

src/content/learn/synchronizing-with-effects.md

@@ -854,7 +854,7 @@ export default function App() {
 
 </Sandpack>
 
-You will see three logs at first: `Schedule "a" log`, `Cancel "a" log`, and `Schedule "a" log` again. Three second later there will also be a log saying `a`. As you learned earlier, the extra schedule/cancel pair is because React remounts the component once in development to verify that you've implemented cleanup well.
+You will see three logs at first: `Schedule "a" log`, `Cancel "a" log`, and `Schedule "a" log` again. Three seconds later there will also be a log saying `a`. As you learned earlier, the extra schedule/cancel pair is because React remounts the component once in development to verify that you've implemented cleanup well.
 
 Now edit the input to say `abc`. If you do it fast enough, you'll see `Schedule "ab" log` immediately followed by `Cancel "ab" log` and `Schedule "abc" log`. **React always cleans up the previous render's Effect before the next render's Effect.** This is why even if you type into the input fast, there is at most one timeout scheduled at a time. Edit the input a few times and watch the console to get a feel for how Effects get cleaned up.