You may use the the_author_meta function:
the_author_meta( string $field = '', int|false $user_id = false )
You may provide $field which is of these values:
admin_color
aim
comment_shortcuts
description
display_name
first_name
ID
jabber
last_name
nickname
plugins_last_view
plugins_per_page
rich_editing
syntax_highlighting
user_activation_key
user_description
user_email
user_firstname
user_lastname
user_level
user_login
user_nicename
user_pass
user_registered
user_status
user_url
yim
and is well documented here. In your case you may choose display_name.
Also you may provide the $user_id. If you don’t provide it, it will be the current author’s DB object (author of current post).
If you want to get the name for some string manipulation and not directly printing on the output, just use get_the_author_meta().