Blacktail Deer Plateau lord of wolves

Rue had sharp senses and nearly always had her guard up. Although the pack had recently taken down a caribou, Rue made sure that she never gorged to the point that her reflexes were affected. She had learned the hard way that you could never be sure when an attack could come or from whom, and even within pack territory you could still be vulnerable.

She was able to respond immediately to the warning bark-- it was clearly a packmate signaling danger. Rue quickly assessed her own physical condition as she sprinted toward the caller. She was well-fed and strong, and able-bodied enough to assist in border defense, if that was the need. 

Rue's honey eyes darted over the scene as she approached, quicking assessing the situation. It seemed the bear had been desperate enough to cross into pack territory, no doubt after what remained of the caribou carcass. It had become quite pungent recently. Rue's packmate was already attacking, which to Rue was either very brave or very stupid. It was quite trusting but also rather presumptuous of the dark woman to believe that others would hear her and respond, ready to jump into the fray beside her. Rue wished she had waited, so that they could have strategized together before simply barreling into what was sure to be a dangerous battle. 

With precious few other options, Rue darted forward. She knew her only course of action was to do what she could to protect her packmate while also keeping in mind her own self-preservation. She stopped two wolflengths away from the bear to acertain that she was out of range of any quick attack. Rue was on her toes, ready to respond. Her body was low, and her head and ears were tucked to protect her vulnerable areas. She barked and snarled loudly at the intruder, attempting to startle it or distract its attention so that her packmate might gain a precious moment to either attack or dodge. 

Can someone really quickly explain the dice system or link me to someplace where it's explained? I didn't want to have Rue attack yet without understanding how the rolls work or what's at stake for her.