If someone calls you perceptive, they mean you are good at understanding things or figuring things out. Perceptive people are insightful, intelligent, and able to see what others cannot.
Perceive means "to see"; so, perceptive is a word to describe someone who is good at seeing. Perceptive is derived from the Latin word percipere which means "to obtain or gather." A perceptive person is good at gathering information and using her senses to take in the world. If you are upset but trying to hide it, a perceptive person is the one who will notice.