Female 6.3mm (1/4" approx) Blade Terminals are what you require, plus a crimping tool. They're also known as Spade Terminals.
They come in different colours according to the thickness of wire you intend to connect, which in turn relates to the current which will be flowing through the wires and switch.
Each colour is available in different blade sizes also, but you require the most common, 6.3mm size, judging by your photo.
One important consideration before twisting the wires around the blade terminals on the switch: are you connecting up a safe voltage/current?
If you're dealing with mains electricity, fit fully insulated terminals before attempting to power anything up. Any loose or frayed wires could make the whole switch body 'live'.
Fully insulated terminals have rubber or rigid plastic sleeves which cover the metal blade part as well as the crimp section.