The rabbis enacted a decree: one may not wear shoes with nails in them on Shabas. The Bavli, Shabas 60, has a lengthy discussion in which it tries to pin down the exact parameters of that decree, i.e. under what circumstances and to what footwear it applies. In the course of that discussion, it notes that the decree applies to a shoe that had had a large number of nails, but had most of them were removed (uprooted), unless only a few remain. However, if it had had a large number of nails and most were cut down so they no longer stuck out of the shoe (but were not removed), then the decree does not apply, even if more than a few remain uncut. In other words, removed nails count as if they were never there (so a shoe can be worn only if there are few unremoved nails), but cut nails count permit a shoe to be worn even if it couldn't otherwise be.
Rashi, in explaining the word "uprooted" ("שנעקרו"), i.e. removed, says as follows:
לגמרי שאין ניכר שהיה בו יותר ד׳ או ה׳ אין טפי לא לוי״ה ולשון חבירו איפכא
[uprooted] completely, that it is not apparent that there had been more. Four or five, yes, [one can wear;] more, no. [???]
I cannot understand the end of this piece of Rashi (the part I marked by question marks). I have no idea what it is saying at all: not what the acronym stands for, nor the import of the last few words (which mean, literally, "and the tongue of its/his friend reversed"). Can someone explain it, please?