Hi Zhao,
I am not sure I understand the question. Please refer to section 7.2 Functional Block Diagram of the datasheet.
SH_A is used for multiple purposes:
1) It is the low side of the high side gate driver.
2) It is monitored to determine if the Vds of the high side (PVDD to SH_A) or low side (SH_A to SL_A) FETs are correct
SL_A is used similarly to SH_A
1) It is the low side of the low side gate driver.
2) It is monitored to determine if the Vds of the low side (SH_A to SL_A) FET is correct
GL_A and GH_A control the low side and high set FETs, respectively
SENSE_N1, SENSE_P1 are optional. If used, it is connected to a current sense amplifier. The current sense amplifier is used to monitor current through the motor.