For example, without any + and - symbols:

<Directory /web/docs>
Options Indexes FollowSymLinks
</Directory>

<Directory /web/docs/spec>
Options Includes
</Directory>

then only Includes will be set for the /web/docs/spec directory. However if the second Options directive uses the + and - symbols:

<Directory /web/docs>
Options Indexes FollowSymLinks
</Directory>

<Directory /web/docs/spec>
Options +Includes -Indexes
</Directory>