To sidestep something is to get around it by changing the subject or doing something else. If a little kid asks you where babies come from, you might sidestep the question by going to get ice cream. Very quickly.
People sidestep questions all the time. When celebrities or politicians don’t want to talk about something, they sidestep reporters’ questions by answering in a long-winded, vague way — or by saying, "No comment." You can also sidestep in a more literal way by physically stepping around things, or stepping to the side in a dance or march. The military term was first used in the eighteenth century, and the figurative meaning followed around 1900.