I'll try to explain it like you're a child, as requested. When you have money in a savings account at a bank, the bank pays you a little money for keeping your money with them. This money that they pay you is called interest. Just as you keep money at a bank, your bank also keeps money at a special bank called the central bank (Riksbank). The repo rate is the the interest rate that the central bank pays your bank to keep money deposited there. When the repo rate is positive, the central bank is paying the private banks to keep money in their "savings accounts" at the central bank. If the repo rate is negative, however, the private banks have to pay the central bank to keep their money at the central bank. So imagine if you had billions of dollars, and the bank made you pay 0.25% of your billions for the privilege of keeping your money deposited there. You would lose millions of dollars, so what would you do? You would probably find other things to invest your money in and keep as little money as possible in your savings account. The theory is that banks will do the same, and that this will stimulate the economy because the banks will lend more money, instead of keeping it at the central bank. In reality, however, this leads to bad investments, more economic bubbles and wasted resources.