Most likely that is supposed to be a 0.047 uF capacitor (meaning a 47 nF one - 47 nanofarads).

Probably small enough to get a ceramic at that point.
Try DigiKey

note: for audio frequency applications (such as a crossover or DC block) a polypropylene- or polyester-film capacitor will provide the best performance and reliability.

for more on what "best" means, and why, you will need to do some reading, such as...
http://www.reliablecapacitors.com/pickcap.htm

ps
1 Farad = 1 x 10^3 milli F (mF)  = 1 x 10^6 micro F (uF) = 1 x 10^9 nano F (nF)

http://en.wikipedia.org/wiki/Metric_prefix

0.047uF = 47nF

"generally" if you see a capacitor value designated with a decimal point, it's value is in uF.  

ps2
there are also capacitors specified in "pF" (picoFarads, or "puffs", = 10^-12 F) but these are predominantly used in radio frequency (RF) applications, not audio frequency applications.

ps3
another way you may see capacitors marked is with the exponent concatenated to the mantissa as follows:

"473" = 47000pF = 47nF =0.047uF

you read this as 47 x 10^-3 = 0.047uF ///or/// 47 x 10^3 pF

ar-jedi

Ceramic is even better, and is easily available in these type of values now.
Film caps have their own set of problems and ceramic is preferred if available.
They have been available in these values (with good voltage ratings) at very reasonable cost for a while now.