Not enough context to be sure, likewise, there could be a doubt of the language.

'Affleurant' could refer tio the fact it is a low-profile / flush-mounting push-button of some kind — but it would take more context (like an image) to confirm exactly what type it is?

Then again, 'affleurant' could refer to the fact that you merely have to "brush" it with your finger to operate it; this could be an ultra-light touch contect design, or it could be a touch-sensitive / tactile one that operates basically by proximity (capacitive / resistive, etc.)

It's pretty much impossible to tell without more context.

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Note added at 30 minutes (2017-08-16 10:24:59 GMT)
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Well, you see, that's already a huge help!

Now we have some description of the button and where it is mounted, that almost certainly rules out my second suggestion — which would be more likely for some kind of array or keypad, rather than an apparently isolated reset button.

So it seems much more likely in fact that this is indeed some kind of flush-mounting button; or posibble it is just the button part that is flush with its surround, i.e. difficult to operate by accident, unlike a conventional button that sticks out.