The Mass Air Flow Sensor (MAF or MAFS) detects the amount of air flowing through the car's intake. It does this by measuring heat changes between a pair of "hot wire" sensors, by comparing current flow through them. It's perhaps not the method I'd have used (those fragile little sensor wires always just make me wince when I look at them) but it generally seems to work okay and it's at least as reliable as the other principal methods of measuring air flow. The MAF sensor depicted below has been removed from the pipe it's normally installed in; it's the MAF in my 1989 Nissan 240SX.
A new MAF often costs about $400, so there is considerable interest in cleaning them. The usual plan is to take a cotton swap and some isopropyl alcohol to it, cleaning the elements gently. The wires are very thin and pressing hard on them will break them, especially if they are old and corroded at all - but if they are, the sensor will not provide an accurate reading anyway and it should be replaced. If you're just brushing with the cotton part of the swab, it will be almost impossible to damage the sensor.
This procedure is virtually identical for any car with a hot wire MAF. Most Import cars I've looked at seem to use a Hitachi MAF, many of which look identical to this one (but with different numbers and maybe a different connector.) Even if they are different, they're all basically like this one.
There are some other kinds of MAF sensor, but the process for cleaning all of them is basically the same as this. As a possibly superior alternative to alcohol and a swab, you might try using an aerosol electronics cleaner and a soft toothbrush. The electronics cleaner should break up anything on there to the point that a soft brush will remove it. I personally use CRC's QD (available at all the auto parts stores near me, anyway) but I don't know that it's the best thing, only that it seems to work. Another kind of MAF sensor has a sort of zig-zag wire on it that can get caked up with grease and soot and respond slowly. Clean it, reinstall.