The Distributor is the server that contains the distribution database.
Configure Distribution at https://msdn.microsoft.com/en-us/library/ms151860.aspx says:
By default, the Distributor is the same server as the Publisher (a
local Distributor), but it can also be a separate server from the
Publisher (a remote Distributor).
SQL Server can support a single Distributor on the local server. If you are trying to reduce the load on the main server you can instead create the Distributor on a remote server.
If the load is heavy, an additional step that would help manage the distribution is to create a distribution database for each database that is being published. This could reduce the contention within each database that might be present in a single distribution database.
Both a local server and a remote server can support multiple distribution databases.
David Poole's article from 2010, Scaling Out the Distribution Database. may provide you more insight. It can be found here: http://www.sqlservercentral.com/articles/Replication/69663/
Both articles are helpful and I have not detailed every step in the setup.