grasp

understanding of the nature or meaning or quality or magnitude of something; "he has a good grasp of accounting practices"

the limit of capability; "within the compass of education"

an intellectual hold or understanding; "a good grip on French history"; "they kept a firm grip on the two top priorities"; "he was in the grip of a powerful emotion"; "a terrible power had her in its grasp"

the act of grasping; "he released his clasp on my arm"; "he has a strong grip for an old man"; "she kept a firm hold on the railing"

hold firmly

get the meaning of something; "Do you comprehend the meaning of this letter?"