Chapter - 1

(The subdivisions of each of these are) more, many kinds, quick, hidden, unexpressed, lasting, and their opposites.
This sentence concludes the explanation of the previous verse (Verse 16), which lists the twelve qualitative variations of perception. When multiplied by the four stages of perception and the various senses, these result in 288 distinct types of sensory knowledge.

Of the object. (17)

original Sanskrit: "Arthasya"

The aforementioned twelve or 288 varieties belong to [ arthasya ] the object (the dravya—substance—or "thing" being perceived).

(These are the attributes) of substances (objects).
This verse clarifies that the qualities described—such as whether a thing is "many" or "hidden"—are characteristics of the external objects being known by the self.

Of the unmanifested, there is only apprehension. (18)

original Sanskrit: "Vyañjanasyāvagrahaḥ"

For [ vyañjanasya ] objects that are in an unmanifested or indistinct form, such as subtle sounds, there is [ avagrahaḥ ] only the stage of apprehension (the first moment of awareness). The three subsequent stages of knowledge, such as speculation, do not occur for these.

(There is only) apprehension of indistinct things.
Jain philosophy distinguishes between the perception of a clearly visible object and the "indistinct" perception (vyañjanāvagraha) that occurs when a stimulus first touches a sense organ—like the very first moment a sound waves hit the ear before the mind has even begun to wonder what the sound is.

Not by the eye or the mind. (19)

original Sanskrit: "Na cakṣur-anindriyābhyām"

[ Vyañjanāvagraha ] (The apprehension of the unmanifested) does [ not ] occur through the [ cakṣuḥ anindriyābhyām ] eye or the mind.
The "non-contact" senses—the eye (which sees from a distance) and the mind (which processes internal thought)—do not experience this specific type of "contact-based" indistinct apprehension. Only the senses of touch, taste, smell, and hearing, which require physical contact with their objects, experience this subtle first stage.