Maîtriserai
Maîtriserai is a French verb conjugation. Specifically, it is the first-person singular future simple tense of the verb maîtriser. The verb maîtriser means to master, to control, to dominate, or to be proficient in something. Therefore, maîtriserai translates directly to "I will master," "I will control," "I will dominate," or "I will be proficient in."
This tense is used to express an action that will take place in the future, with certainty