When
you create a new site, app, column or page, you need to
give it a name. This name can be changed later, but the
first name will always be kept in what is called the internal
name.
Internal SharePoint names should not have spaces. That is
why you sometimes see irritating extra characters in URLs
when the name has a space. These characters are added automatically
by SharePoint to avoid a space, but using CamelCase naming
will give better URLs.
CamelCase naming is when you write two separate words together
without a space and use capital first letters in both words.
SharePoint is a good example.
When you use the modern experience, SharePoint removes spaces
in app and column names and in automatically created URLs.
In other URLs the spaces can be visible, but spaces can
still create problems, for example when you use SharePoint
names in programming.
In this tutorial, Peter Kalmström shows how you can have
both correct internal names, nice looking URLs and good
app names. He uses an app as example.
Open the settings gear and click on 'Add an app'.
Add any app.
Type the name in CamelCase that you want to give
to your library app and click on Create.
Open the newly created app.
Now you have a good URL without spaces, but the app name
might not be what you want. To change it, do like this.
(The URL will not be changed.)
Open the list/library settings.
In the Settings page, click on the link List name
description and navigation.
When
you create a new site, app, column or page, you need to
give it a name. This name can be changed later, but the
first name will always be kept in what is called the internal
name. 
