Our Mishnah continues its discussion of the measures for carrying on Shabbos - the minimum quantity of each item for which one is liable when carrying it from one domain to another on Shabbos. For the items listed here, even the smallest possible amount is enough to create liability.
Items whose measure is "any amount at all":
"Pilpelet" - a single peppercorn is enough. Pepper was used by someone with bad breath, to lessen the unpleasant odor, and even one grain serves that purpose.
"Itran" - a by-product of tar, used as fuel for burning. Even a small quantity of it was used for medicinal purposes, as a remedy for a headache, and therefore even the smallest amount is useful.
"Minei besamim u'minei matachos" - types of spices and types of metals, in even the smallest amount. With spices, one can smell even the tiniest bit, and from metal one can fashion a very small utensil, such as a small needle or the like.
Items of sanctity:
The Mishnah goes on to list: stones that have worn away from the Altar in the Beis HaMikdash, earth that has fallen from the Altar's plaster and the like, worn out Torah scrolls, and worn out pieces of the wrappings of a Torah scroll. In all of these too, the smallest amount is considered significant, and one who carries them out on Shabbos is liable.
The reason is that all of them are put away, even in a minute quantity, for genizah - that special place where the items known nowadays as 'shaimos' are kept. Since they possess sanctity, whether the items come from the Altar or from a Torah scroll, they may not be discarded, but must be set aside and preserved in a special place. For this reason even the smallest amount is significant and creates liability.
The view of Rabbi Yehudah - accessories of idolatry:
Rabbi Yehudah adds that one who carries out or transfers on Shabbos items that were used for idolatrous purposes is also liable for any amount at all. Here the reason for their significance is not sanctity, since they contain no sanctity whatsoever, but rather the verse stated regarding idolatry and its accessories: that nothing at all should remain in one's possession, not even a small quantity, of that which must be destroyed.
Therefore, one who carries out of his house or transfers on Shabbos even a small quantity of an idol or of its accessories is liable, since even the smallest amount requires destruction, and by virtue of that it is considered significant.
In summary: This Mishnah lists items whose measure for liability for carrying on Shabbos is "any amount at all": pepper and tar, because even a minute quantity of them is fit for use and for healing; types of spices and types of metals, because even a little of them is useful; stones of the Altar, its earth, and worn out Torah scrolls and their wrappings, because they are put away for genizah on account of their sanctity; and according to Rabbi Yehudah, also the accessories of idolatry, since nothing of them may remain in one's possession.