Welcome to Nestwell Property Managements 24/7 DIY Maintenance Center.
Thank you for your question concerning the leak under your kitchen sink. Please use a towel to clean up any puddles that might be standing. Then place a bucket, pot, pan, or some other large container under the pipe that is leaking, and turn off the water supply to the sink.
The following video will give you instructions on how to turn off the water supply to the sink:
Then, complete a service request online. Please be sure to mention that you've shut off the water to the sink in the request.
If you cannot get the water to stop, please follow the instructions for a maintenance emergency.