Prior to taking CCNA Security you will need to pass the CCNA Routing & Switching exam or CCENT.
How much time does it take to study and pass CCNA Security? Going through the exam, I would estimate around 3-6 months if you have minimal exposure to Cisco technologies. A lot of what is on the exam overlaps with the CCNA certification.
Do you need a lab to pass the exam? Labbing isn’t required but is highly recommended. You can perform most of the labs using GNS3 or Packet Tracer. One area to be knowledgeable of is Cisco Configuration Professional, which you can download and use against Cisco routers. I recommend using the CCNA Security Lab Companion.
My CCNA Security PDF of my notes should be used as a supplement to the official CCNA Security study guide.