Rashi and Rashbam: It refers to where, after eating the Nivlas Of Tahor, he eats Kodesh or enters the Mikdash, ¹ which renders him Chayav Kareis like any other Tum'ah.

Seforno: It means that someone who eats Nivlas Of Tahor will suffer the consequences according to the sin that he perpetrates in his Tum'ah, depending on whether he ate Kodesh (or entered the Mikdash) or merely touched it, or whether he simply rendered Chulin Tamei. ²

Rashi: To teach us that he is only Chayav Kareis if, before Toveling he eats Kodesh or enters the Mikdash, but if he brings his garments into the Mikdash before Toveling them, he only receives Malkos. ¹