What is the approximate pH of the salivary secretion? Is it an acid or basic fluid? What are the main functions of saliva?

The saliva pH is approximately 6.8. It is therefore a slightly acid pH.

Saliva lubricates the food bolus and initiates the enzymatic extracellular digestion of food. It also works as a buffer for the mouth pH and it has an significant role of having IgA antibodies (also present in tears, colostrum, mother's milk and in the mucosae of the intestine and airways) that protect the organism against pathogens.