It effectively means the distance the handle moves compared with distance a sheet round the winch will move. For example if the winch has no gears and the drum turns at the handle speed, then it is the ratio of the length of the winch handle to rhe radius of the winch drum. As more reduction gearing is added then the winch gearing increases. The ratios are normally quoted for a 10" handle (I think).
What I do not understand however is, why does some enterprising manufacturer not introduce a 12" or 15" winch handle?.