practicing
v.v. to do an activity many times so you can get better at it. You also use this when you work in a professional job like law or medicine.
v. to perform an activity or exercise regularly to improve or maintain proficiency; to work in a professional field such as law or medicine. Transitive when taking an object, or intransitive when describing general activity.
She is practicing the piano for her concert.
After finishing law school, he spent several years practicing criminal law at a small firm downtown.
While the athlete was practicing her serve, she noticed a slight tension in her shoulder that required immediate attention from the team physiotherapist.
The spelling 'practicing' is standard in American English for both the verb and the noun; in British English, 'practising' is the verb and 'practice' is the noun.
He is practice the guitarHe is practicing the guitarLearners often use the base noun form instead of the present participle when describing an ongoing action.