Frequency means the time interval you wish to place your SIP orders (after the start date). The first order will be placed on the 'start date' as specified by you and thereafter subsequent orders will be placed at the defined frequency for the specified 'period' as per your request.
You have an option to select Daily, Weekly, Fortnightly and Monthly frequency
For example:
Monthly SIP - If you have placed an Equity SIP request for buying 100 shares of Axis Bank for a period of 6 months by choosing start date as 05-Mar-2012, your first SIP order for 100 shares in Axis Bank will be placed on 05-Mar-2012 and subsequent SIP orders will be placed on 5th of every month (05-Apr-2012, 05-May-2012 and so on) for the next 5 months.
Fortnightly SIP - If you have placed an Equity SIP request for buying 50 shares of Axis Bank for a period of 2 months with start date as 05 Mar 2012, your first SIP order for 50 shares in Axis Bank will be placed on 05-Mar-2012 and the subsequent SIP orders will be placed on 19-Mar-2012, 02-Apr-2012 and so on with an end date of 04-May-2012.
Weekly SIP - If you have placed an Equity SIP request for buying 25 Shares of Axis Bank for a period of 2 months with start date as 05-Mar-2012, your first SIP order for 25 shares in Axis Bank will be placed on 05-Mar-2012 and the subsequent SIP orders will be placed on 12-Mar-2012, 19-Mar-2012 and so on with an end date of 04-May-2012.
Daily SIP - If you have placed an Equity SIP request for buying 10 Shares of Axis Bank for a period of 2 months with start date as 05 Mar 2012, your first SIP order for 10 shares in Axis Bank will be placed on 05-Mar-2012 & the subsequent SIP orders will be placed on 06-Mar-2012, 07-Mar-2012 and so on with an end date of 04-May-2012.