I'm not able to sync my iPhone6s, Have 2 Macs. I'm able to sync on one mac but not able to sync on another one. Need guidance.

It helps to tell us at the start what happens when you try to sync.

- Exact working of error messages.

- What kind of connection are you using?

What is likely is a device can only sync to one library at a time. Unless you are using the exact same library on both computers it will offer to erase before syncing to a different library.