In one sentence, describe what the following article is about:

This app allows you to view several different aspects of your Android's system use, including RAM:  Open the {"smallUrl":"https:\/\/www.wikihow.com\/images\/1\/1e\/Androidgoogleplay.png","bigUrl":"\/images\/thumb\/1\/1e\/Androidgoogleplay.png\/26px-Androidgoogleplay.png","smallWidth":460,"smallHeight":531,"bigWidth":"26","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of an Android icon\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Fair_use\">Fair Use<\/a><br>\n<\/p><\/div>"} Play Store. Tap the search bar. Type in simple system monitor. Tap Simple System Monitor in the drop-down results. Tap INSTALL, then tap AGREE if prompted. Tap OPEN in the Google Play Store, or tap the blue-and-white Simple System Monitor app icon in your Android's App Drawer. This will take you to the main Simple System Monitor page. It's at the top of the screen. Depending on your Android's screen size, you may have to swipe left across the tabs at the top of the screen to view the RAM option. You'll find the currently used RAM in the bottom-left corner of the screen, while your Android's total available RAM (e.g., RAM not reserved for use by the system) is in the bottom-right corner.

Summary:
Install Simple System Monitor. Open Simple System Monitor. Tap OK when prompted. Tap the RAM tab. Check your used and available RAM.