You're gonna get a lot of slang names but 3M call it an "Fully Insulated Female Quick Disconnect Terminal":
https://www.amazon.com/Nylon-Insulated-Female-Disconnect-Terminals/dp/B003IADEAW/
red is for wire sizes 18, 20 or 22AWG.
blue is for 14 and 16AWG
yellow is for 10 and 12AWG
pick the size you need based on what's written on the wire rather than what's there already because people sometimes use the wrong sizes...