This is a Ghost protection charm. This one is from the unique exorcism rites which are available and in practice in India. The charm is a Yantra [geometrical design] corresponding to the letter LAM or लाम् in Sanskrit. This is the single letter mantra of the Muladhara; the basic chakra.
This chakra on the lower levels vibrates to lower entities, vibrations and energies and hence needs to be strengthened to deflect such energies which become attracted to someone having a blocked or weak Muladhara chakra.
If this charm is written on a Bhojpatra, with Gorochana using a pointed wooden stick, it is said to give protection from Ghosts and mystic entities like Pishachas and Dakinis and also from any kind of unknown fever. The charm has to be kept on the body of the person who want this kind of paranormal protection.
Other than this there are no other rules prescribed; like the chanting of a mantra or stotra. The drawing is given as a guideline; actual drawing on the Bhojpatra might differ.