when a new node(server) with empty data is be online and becoming a slave of what c

[superwood]

when a new node(server) with empty data is be online and becoming a slave .

What will happen?

[carlosefr]

It is populated with whatever the master has in its (binary) logs. Data already present in the master but whose transactions have been deleted are not replicated.

The best way to initialize a slave is by dumping all data from the master and importing it into the slave before turning it into a slave. Whatever the master has in the logs will them result in a consistent state.