I picked up a 10 pack of Durex 'Play' sachets in Superdrug for £2.99 on a buy one, get one free offer. We'd previously used sample of the normal 'Play' lubricant and found it very good, alas though, in Superdrug the original variety was out of stock and I think sometimes, a change is as ... Read review
It's just a form of lubrication.
You have to first turn the top into a position where you can push it down. It will the dispense the lube. Apply it onto the penis/toy and apply it to the vagina/anus.
It is designed as a lubricant so it is fine for internal use. And what should be an added bonus is the application to any erogenous zones (such as the clitoris) to create a more intense orgasm.