The name Iscah in the Bible
There's only one Iscah mentioned in the Bible. She's the daughter of Haran, and the sister of Milcah and Lot (Genesis 11:29). It's a bit peculiar that we don't hear any more of this Iscah—she is after all the niece of Abraham. Some scholars believe that Iscah is the same as Sarah, Abraham's wife. This by itself would not be that odd since Iscah's sister Milcah marries Abraham's brother Nahor. Still, in Genesis 20:12 Abraham informs Abimelech that Sarah is the daughter of Abraham's father Terah, so it seems far more likely that Iscah is not the same person as Sarah.
Etymology of the name Iscah
The meaning of the name Iscah is difficult to establish. BDB Theological Dictionary deems the "etymology dubious," so dubious even that they don't even attempt one. NOBSE Study Bible Name List and Jones' Dictionary of Old Testament Proper Names go with an used verb סכה (sakah) or שכה (sakah), meaning to look at:
For a meaning of the name Iscah, NOBSE Study Bible Name List reads Watchful and Jones' Dictionary of Old Testament Proper Names has She Will Look Out, or She Will See.