To be fully capable of performing a job or task and to do so with ease and satisfaction; to be well qualified and happy in one's work.

(idiom) to be unequal to a task or position; to lack the strength or ability to handle a responsibility

unable to manage a task or responsibility; strength or ability falling short of what is required

lacking the talent or ability to handle a task or responsibility; one's capability being inadequate for the position

the ability to do a job or task effectively; competence