Pramaan translates as proof or a valid cognition. It is of three kinds: pratyaksh is the pramaan that is perceived directly by one or more of the five senses (e.g. you see fire on the mountain); anumaan is the pramaan that you get by deriving conclusions/estimating from the symptoms that are directly perceived by your senses (e.g. you see smoke on the mountain, and you deduce there is fire); aagam is the pramaan you get by hearing/reading from an authority.

It is important to note here, that whether it is directly perceived or deduced by you or revealed to you by a credible source, whatever you see, hear, touch, smell, taste, infer or get to know, Patanjali terms all of them as vrittis of the mind which need to be stilled to achieve yog.