We can use ISODD function to Highlight the odd rows in Excel:
1. Select the cells that want to be highlighted.
2. Select Conditional Formatting
3. Select Highlight cells rules
4. Select more rules.

5. In the New Formatting Rule tab you will see all Rules.
6. Select Use a formula to determine which cells to format.
7. write the below code in Format values where this formula is true.
=ISODD(ROW())
8. Select Format.

9 and 10. in the Format Cells, Select the Fill tab.
11. Choose your desired Color.
12. Select OK.

9. You will see the results in the following picture.

ISODD function
The ISODD function is one of the Information functions of Excel. It Returns TRUE if the number is odd.