Syntax:

global class class_Name Implements Database.Batchable <sObject> {

    global Database.queryLocator start( Database.BatchableContext bc ) {

        String strSOQL = 'SELECT Id FROM sObject';
        return Database.getQueryLocator( strSOQL );

    }

    global void execute( Database.BatchableContext bc, List < sObject > scope ) {
    }

    global void finish( Database.BatchableContext bc ) {
    }

}

To execute:

Class_Name obj = new Class_Name();
Database.executeBatch( obj );

To schedule:

global class Scheduleclass_Name Implements Schedulable {

    global void execute(SchedulableContext sc ) {

        Class_Name obj = new Class_Name();
        Database.executeBatch( obj );

    }

}