Most keywords (traits) are pretty self-explantory and, with a recent update, in-game tooltips help to explain each trait too.
Here's a slightly deeper explanation of a handful of keywords that can cause confusion.
We don’t want the excitement to end, so we’re bringing Capture the Flag to the Arcade as an ongoing game mode.
Starting today, we’re adding Capture the Flag versions of Nepal, Lijiang Tower, Ilios, and Oasis, which gives you 12 maps to try when creating a Custom Game.
New Mode: Capture the Flag Capture the Rooster has been, without a doubt, Overwatch’s most popular brawl.
Aura - Some units (Spartan, Aphrodite) can impart an aura, either by ability or as a passive trait.
Auras let friendly characters absorb a certain number of damage EACH TIME the unit is attacked (though Aphrodite's aura only lasts two turns).
See them below or on Play Overwatch.com: New Feature: Game Browser Starting today, every player can create their own, unique Overwatch experience and share it with their friends, teammates, or the entire world. An extension of Overwatch's Custom Game mode, the Game Browser allows you to adjust the settings on various maps, modes, and heroes to create your own tailor-made match.
For example, if you want to increase the speed of Pharah’s rockets or remove the cooldown from Mc Cree's Combat Roll, the power is yours.