This is the maximum amount you can invest in any one Mutual Fund scheme at any specific time. We keep this high enough so that when you get your bonus or pay hike, you can quickly make an investment without the paperwork to increase the bank mandate.
We can only ever transfer funds out of your bank account as per your instructions. You may never use this limit, or may find this limit too low. Go to Account settings -> Bank -> Edit to increase the bank mandate or change your bank details.