See the guideline of licenses policy:
https://spdx.org/licenses/
https://community.kde.org/Policies/Licensing_Policy

Usual usages:

BSD-3       : cmake, sh, rb, py, pl.
GPL2+/LGPL2+: cpp, c, h, xsl, conf, nsh, nsl.
CC0-1       : yml.
MIT         : css, js.