#ITEM PAID NO FUNDS 1 ITEMS ON every week

I don’t understand FNB its like every week I get charged with the reference: #ITEM PAID NO FUNDS 1 ITEMS ON. I was never made aware of this fee and i would like to know what this is for and why it’s all of a sudden started coming off of my account? This week I was charged R60 and R30 both #ITEM PAID NO FUNDS 1 ITEMS ON