As a dancer who is taught meticulous detail, instructed on what to do - and when and how - sometimes it can be difficult to take the lead and add your stamp to choreography. Teachers might encourage you to improvise for eight counts mid-routine, or simply expand what has been taught, but this is harder for some dancers than it is others.
What does “make it your own!” mean? If you have been pinning the routine down for the last hour, correcting mistakes and getting to grips with the different aspects required, it may then be difficult to 'own' the routine if you have spent so much time dancing it in the style of the teacher. Despite this, many dancers find it easy to inject their own feelings into the choreography from the start of teaching.
With that statement, the teacher is simply letting you know that you have some freedom to interpret the movement. It may be less of an invitation and more a reminder, that the teacher would like to see your personality shine through the choreography. Now you are familiar with the movement, and have practised it with increasing accuracy, it is the aim to add more to simply replicating steps, timing and movement quality.