This is a Class D stereo 3W amplifier with a volume control (that has an integrated power switch).
Based on the PAM8403 Amplifier IC (Google for datasheet), this little board provides left and right Class D outputs to drive 4 or 8 Ohm speakers, one per channel.
Output power (into 4 Ohm speaker and supply voltage of 5v) is up to 3W per channel.
The board is silk screened to show you the connections, namely, + and - for the right speaker, + and - for the left speaker, power + and -, and the input Left, shared input ground, and Right.
This amplifier is the perfect companion to the JQ6500 Mp3 Modules which I also sell so you can get stereo output instead of just mono.
CAUTION! This is a Class D amplifier, this means that the two speakers must be totally separate (each has a + and - totally separate from the other), you can not use this amplifier to drive headphones because headphones have their speakers connected at a common point, if you were to connect any of the ROut to any of the LOut, you are effectively short circuiting the amplifier, so don't do that!
PS: Bit of a tip for you when it comes to picking some speakers to build into your sizeable project - have a look in The Warehouse at their twin packs of "American Hi-Fi" car audio speakers, 2 4 Ohm speakers and all the mounting stuff for just $20 (even cheaper sometimes) is quite simply unbeatable in value, even direct from China can't come close.
All of our products are shipped from Christchurch, New Zealand using CourierPost for NZ, and Airmail for international.