org-export-with-section-numbers

org-export-with-section-numbers is a variable defined in `ox.el'.
Its value is

t

Documentation:
Non-nil means add section numbers to headlines when exporting.

When set to an integer n, numbering will only happen for
headlines whose relative level is higher or equal to n.

This option can also be set with the OPTIONS keyword,
e.g. "num:t".

You can customize this variable.