원인

org.mybatis.spring.MyBatisSystemException: nested exception is 
org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for 
the Mapped Statement 'mapper.manual.폴더명.폴더Mapper.getAdsCount'.  
It's likely that neither a Result Type nor a Result Map was specified.

해결

<select id="getAdsCount" parameterType="java.util.HashMap" resultType="java.lang.Integer">
</select>

resultType 지정해주니 해결되었다