This command returns contents of the whole directory.
Option -x tells the command that you want to use simple authentication instead of SASL. To search LDAP directory for an entry we will be using ldapsearch utility. It also shows the basic configuration for OpenLDAP client which makes it possible to send requests to the server. You might want to read this post which explains step by step how to install and run OpenLDAP server on Ubuntu 18.04. I assume that you have a working OpenLDAP server and OpenLDAP client.
In this post we will learn how to search OpenLDAP directory using ldapsearch command.