Since you don't understand the word I'll give you some help:

Definition:
[n]  the activity of exerting your muscles in various ways to keep fit;
    "the doctor recommended regular exercise"; "he did some
exercising"; "the physical exertion required by his work kept him fit"
[n]  a task performed or problem solved in order to develop skill or
understanding; "you must work the examples at the end of each chapter in
the textbook"
[n]  systematic training by multiple repetitions; "practice makes perfect"
[n]  the act of using; "he warned against the use of narcotic drugs";
"skilled in the utilization of computers"
[n]  (usually plural) a ceremony that involves processions and speeches;
"academic exercises"
[v]  do physical exercise; "She works out in the gym every day"
[v]  give a work-out to; "Some parents exercise their infants"; "My
personal trainer works me hard"; "work one's muscles"
[v]  learn by repetition
[v]  put to use; "exert one's power or influence"
[v]  carry out or practice; as of jobs and professions; "practice law"

Hope this helps