If you are entering the zeros directly, Numbers will display what you entered.
If the zeros are the result of a calculation done by a formula in the cell you could wrap the formula in an IF statement to return a null string is the result of the formula is zero.
IF(formula = 0,"", formula)
Example:
Each cell in column A has the formula "RANDBETWEEN(0,5)" entered to generate a random integer in the range 0 to 5. The checkbox in Cell A1 serves as a pushbutton that makes all formulas in the table recalculate each time it is clicked.
The formula shown below the table is placed in all cells (except B1) of column B. The formula passes the number if it is not 0, and replaces it with an empty string if it is zero.
In the second example, below, the conditional highlighting is done on the values in column A, using the rule shown in the side bar. I the number in the cell is 0, the rule sets its colour value to 255 255 255 (red, yellow and blue are all set to their highest concentration) with the result being white numerals on a white background.
Regards,
Barry