This tab contains information about last 20 matches. These are scores, number of kills, assists, and deaths, as well as IP gained. Clicking on one of the matches on the right side of the screen reveals additional information, such as sum of all damage points dealt to enemies, creatures killed, and gold gathered. You can also learn which items were used by a given champion in the game. Matches from the current patch version can be downloaded as replays. You can run them on the game's engine and get the most important moments that you want to save as highlights.
Besides that, you can also check other tabs with detailed information presented in a form of graphs or stats.