Don't hide passwords in Excel.  If you hide passwords in Excel, they can be found.  If you password protect Excel documents, they can be cracked.  Now that I've given my public service announcement, if you have to hide passwords in Excel or you have data that you don't necessarily want visible at all times, I have a quick fix for you.   I was sort of hoping for something a little more elegant but when I came across this solution, it solved my immediate problem and I'm not really all that interested in spending more time for a slightly better solution.

Below, we have a typical Excel document with a column for the username and another column for the password:





Unless you also want to hide the column header, only select the data you wish to hide:





Upon creating your selection, right click and choose Format Cells:





Under Category, choose Custom and for the Type, enter three semicolons:





When we choose OK:





Our passwords vanish but when we select on one of the fields:





We see the password appear in the value field.  If we select into the value field:





The password appears in its data field.  When we select into another area of the document:





Our password disappears. 

Again, this is a fairly low budget fix but it works well.