||When you eventually build a stone altar for Me, do not build it out of cut stone. Your sword will have been lifted against it, you will have profaned it.
Ve'im-mizbach avanim ta'aseh-li lo-tivneh ethen gazit ki charbecha henafta aleyha vatechaleleha.
||Do not climb up to My altar with steps, so that your nakedness not be revealed on it.
Velo-ta'aleh vema'alot al-mizbechi asher lo-tigaleh ervatcha alav.
This is saying that a permanent stone altar would have to be built eventually, for the Holy Temple. It was built of stone and filled with earth. (Mekhilta; Rashi). See Exodus 27:1.
Instead, it had a ramp (Mekhilta; Rashi).