It is a more subtle psychic gifts, and the person who has this ability (it can be taught and learned) receives messages through visions, pictures and symbols.
One of the main ways people experience these is through the Third Eye Chakra, as this is where we receive messages from our spirit guides. No two clairvoyants will see the same thing. This second sight can come in variety of forms from a single snapshot of an image, moving pictures, or a symbol of some kind that has relevance that you or the person you are helping knows.
This gift is one of the many learned gifts, as spirit guides send us messages through our intuition, through gut instincts or random thoughts in our heads, to actual pictures.
To develop this gift, it's important to build a connection to your spirit guides as they are the ones who are sending the messages. Practicing visualization is important as well. Meditation is also a good tool to use as well, as this is where you can ask your spirit guides for help, and for them to send clearer signals. Also opening your third eye chakra is important as well. Also, having a high vibrational energy level can help images be more clear and come more frequently, and this means, simply put, that spirits vibrate really fast because they are not weighed down by a physical body, so it's important for us to meet them half way by raising our vibrational energy which can be done by doing what makes you happy in life, and staying away from negativity. Doing this not only makes it easier to receive messages, but it also gains the trust of your spirit guides as well.
Through meditation and communicating with your spirit guides. Do some chakra meditation, clear out any negativity inbuilt life, do regular meditation and invite your spirit guides to talk and communicate with you. It's a personal journey.