PostgreSQL: What is data replication?

I read from a post about comparing MySQL and PostgreSQL, there is one who said:

The biggest disadvantage of PG for me had been the lack of replication, but it's recently gotten both asynchronous and synchronous replication.

Source: https://www.quora.com/What-are-pros-and-cons-of-PostgreSQL-and-MySQL

So my question is: What does that "PostgreSQL lacks replication" mean?