Explain code lines

Using Arduino Programming Questions
1

hey guys,
I need explain for some code lines

#include "SD.h"
#define SD_ChipSelectPin 10
#include "TMRpcm.h"
#include "SPI.h"

TMRpcm tmrpcm;

tmrpcm.speakerPin = 9;

thanks in advance

2 
#include "SD.h"  //include the SD library.  The library files are in the same folder as the sketch
#define SD_ChipSelectPin 10  //define the pin to be used as Chip Select for the SD reader
#include "TMRpcm.h"  //include theTMRpcm library.  The library files are in the same folder as the sketch
#include "SPI.h"  //include the SPI library.  The library files are in the same folder as the sketch

TMRpcm tmrpcm;  //declare a TMRpcm object named tmrpcm

tmrpcm.speakerPin = 9;  //set the speaker pin for the tmrpcm object to 9