The rule is that whenever somebody commits a lav, they violate a Torah prohibition and receive malkot (lashes). The question becomes: When a person is an ed zomem, when he gives testimony falsely about somebody else and tries to cause them a certain punishment, we've said that they already receive a punishment in that they now receive the punishment they were trying to plot on somebody else. Do they also receive malkot, or is it simply that they receive the punishment they were trying to plan for somebody else?
Let's say we had witnesses who testified that somebody owed his friend 200 zuz (a currency unit), and they committed a sin. It was found out that the person was an ed zomem, that his testimony was false, and that he was in a separate place—he was somewhere else—when that transaction supposedly occurred. We say that he is given malkot for violating a lo ta'aseh (negative commandment), and he also has to pay the 200 zuz that he was trying to cause somebody to lose out on. Shelo hashem hamevi'o lidei makkot (That the prohibition bringing him to lashes is not...). The reason is that the two punishments we're talking about here—malkot and the fact that he has to pay money—come from two separate prohibitions. He's receiving malkot because he gave false testimony, as the pasuk (verse) says: lo ta'aneh b're'acha ed shaker, you shouldn't bear false witness against your friend. And he's obligated to pay as an ed zomem, where the pasuk says: va'asitem lo ka'asher zamam, you do to him what he was plotting to do to somebody else. Therefore, he gets both punishments: he has to pay, and he also receives malkot. This is the opinion of Rebbe Meir.
But the rabbis argue with Rebbe Meir and say that whoever pays as an ed zomem is not given malkot as well. A person cannot be punished for two separate penalties with one single aveirah (sin), with one single crime. The ed zomem here is paying the 200 zuz for the aveirah, so they are not given malkot as well. The pasuk says, "He's punished according to his wickedness," and seemingly, it's talking about one single wickedness; therefore, he cannot receive two punishments. This is the idea expressed by the Hachamim (the rabbis). Anytime we have a conflict—should he have to pay, or should he receive malkot?—mashma (it implies): we see from here that he has to pay, and he would not receive malkot, as opposed to receiving malkot and not having to pay.