In a RAW editor, the Exposure control usually applies a gain/multiplier to the RAW sensor data (or to very early linear image data). In practice, this is much like changing exposure or ISO by a number of stops before the image is rendered.

So yes: it largely simulates a different in-camera exposure, but only within the limits of the data already captured. It cannot recover detail that was never recorded, especially clipped highlights.

RAW files store roughly linear sensor values and usually contain more dynamic range than the final JPEG/display image. The Exposure slider shifts how those recorded values are mapped into the final image tone range. The RAW file’s true minimum and maximum recorded values do not change; the rendering’s black/white placement changes within that captured range.

This differs from a Brightness adjustment, which typically targets the rendered image more broadly, often emphasizing midtones and trying to preserve black and white points rather than simply applying a straight linear amplification.

In short: Exposure in RAW processing is usually an early-stage linear amplification/remapping of captured sensor data, not just a generic brightness filter.