I got every part you told there, except ETH address.
How can someone be traced through it actually?

The possibility to be anonymous or pseudonymous relies on you not revealing any identifying information about yourself in connection with the bitcoin addresses you use.  If you post your bitcoin address on the web, then you're associating that address and any transactions with it with the name you posted under.  If you posted under a handle that you haven't associated with your real identity, then you're still pseudonymous.