You set up the device with a view of the area you want to monitor. You can designate an area of the screen to monitor and if the device sees movement in that area, you can be alerted. You can also start a video chat with the device. The traffic is encrypted to ensure privacy. Alerts could also be used to turn on lights or activate other Internet of Things devices in your house.
They're currently offering it as a free service, but will likely charge for it at some point. While the camera devices can be pretty much anything you own that runs Chrome, the remote device for receiving the alerts and conducting video chats currently needs to be an Android 4.1 or better device (iOS and smart TV versions are coming later.)
Go to http://getperch.com for more information. You can download the Android app from the Google play store.