This is a dictionary question. You could check the dictionary and then send us your context with your guess as to what the word means in context. "jerk" has at least three different meanings I can think of.

With respect to a rope or a chain or anything mechanical, it means a sudden pull, or a motion that starts and stops. "Ahab first paid out more line: and then was rapidly hauling and jerking in upon it again." "[Santa Claus] filled all the stockings, then turned with a jerk..." "Use this software to smooth out your jerky video footage..." With respect to a person, it's an informal, insulting word. It means someone who is socially clumsy, annoying, or contemptible. "People who try to use italki as a dating site are jerks."