Slice of life, or "nichijou" in Japanese, refers to events that occur on a daily basis such as getting ready for the day, light chores, enjoying a hobby, or preparing meals. These events differ depending on setting, but above all else are considered to be ordinary, everyday actions that don’t always follow a central plot. The related tags School Life and Work Life focus on ordinary events that take place in a school or work setting, respectively.
Mecha are self-propelling machines that are modeled after humans; some can change into multiple, non-humanoid formats as well. They're usually controlled by an internal pilot or by remote, but are sometimes sentient beings that move autonomously. A mecha's size ranges from bulky, wearable armor to a massive, towering contraption and beyond. While mecha have a wide range of applications, such as making manual labor easier, they are most commonly portrayed as heavily-armed war machines.
Drama anime heavily emphasize their characters' emotional development. Whether by experiencing the protagonist’s emotional turmoil, viewing heated character interactions, or exploring a passionate romance, any anime that humanizes its characters through emphasizing their flaws qualifies as a Drama.