The Language Trick is a glitch in the game, that can be used to generate more Yard items at Locations and Quest Locations. This is helpful if a quest requires you to clear a certain item that you've already cleared, and need to generate more. In most cases, items will respawn normally if you refresh the game page - but using this trick works faster and for nearly all of the yard items.
EA seems to have fixed this glitch, with the "Case Of The Missing Sim" quest. "Evidence bags" are not respawning without a refresh, and switching languages doesn't help.
Simply click on the Settings Menu icon on the top right of your game screen (looks like a wrench). Then click on the language button with the flag on it. It will bring up a screen that looks like the one to the right.
Choose another language from the menu and click ok. The screen will blink, and more yard items will appear. You may have to change the language several times to get enough of the item you want.
When you have enough, just change it back to your normal language. You can also refresh the page to get rid of the extra items.
Using this trick will spawn the yard items at random, and refreshing the page when you're done can help to clear some of them - but not all of them. You will end up with all the extras in your yard until you clear them. In some cases, using this trick at one location will also make more yard items appear at your Home or Beach House.