You're using an Electrum 2FA wallet... as per the notice during wallet setup, the 2FA wallet charges a small fee per transaction for the 2FA service (operated by third party TrustedCoin). The fees charged by TrustedCoin are "prepaid" in chunks of 20 or 100 transactions.

You can read more about the service and the costs here: https://api.trustedcoin.com/#/electrum-help

You have paid for 20 credits with your 0.001... you now have 19 "credits" left before you have to pay again