Attributes represent not only how strong you are, but how much energy you have in a type of ability before you exhaust yourself. You can use attribute points to boost rolls, which makes the same attribute number noticeably stronger in Wayfarers than in D&D.
Pushing an attribute when you have nothing left to push gives you a level of exhaustion. See Exhaustion and Wounds.
Why boosting?
The designer was never a fan of spammable spells like guidance. Boosting is a limited, attribute-based way to improve a roll.
Some abilities cost a Boost, such as Beastcaller’s Exceptional Training and Critter Dispersal.
Surge
From the Additional Info notes: Surge is pushing your abilities. It expends your attributes, but gives you a class point. You can spend class points on special skills.
How does boosting work?
The headings “Pushing/Boosting” and “What’s the point of boosting?” have no rules yet: how many points you can spend, what a point adds, and how points recover.