If you make a copy of something, like a form or a picture, you have made a replication of it. You might need to mail in a replication of your tax forms when you apply for college financial aid.
When you conduct an experiment, you have to repeat it several times to verify that your hypothesis is correct. Each repetition is one replication. A witty retort to a comment or question is also called a replication. Your replications to the teacher's questions may make your classmates laugh, but your smart mouth is bound to get you in trouble eventually.