There are two main ways you can pay your insurance: the full sum to cover the next 12 months upfront, or in 12 monthly instalments over an annual period.
The major drawback to monthly payments is paying by instalment usually makes the total cost of cover higher than it would be if you paid in one go. This is because the insurance company is effectively lending you the money to pay the premium, so it will charge you what amounts to interest on the repayments you make across the year.
By paying In full you are clearing your entire payment all in one go, meaning the insurance company won’t have to lend you the money and you won’t be due any premiums on the loan.