Hi Sarah :)

what do we mean by listen state here?

They receive HSRP hello packets but they do not send.

http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_hsrp_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1054608

Do others routers, not active hrsp and standby hrssp, not transmit hellos, they just listen hellos from active hrsp router and stand by hrsp router?

Correct.

How many hrsp groups can be configured on physical interface ?

The answer depends on the hardware. For instance:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_qanda_item09186a008011c6bb.shtml#q6

what type of interface can use hrsp?

LAN interfaces, HSRP provides high network availability by providing first-hop routing redundancy for IP hosts on Ethernet, Fiber Distributed Data Interface (FDDI), Bridge-Group Virtual Interface (BVI), LAN Emulation (LANE), or Token Ring networks configured with a default gateway IP address.

http://www.cisco.com/en/US/docs/ios/ipapp/configuration/guide/ipapp_hsrp_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1061902

3)How many virtual router address a hrsp group could have?

You can have a primary and secondary.

http://www.cisco.com/en/US/docs/ios/ha/command/reference/ha_s3.html#wp1044135

HTH,

__

Edison.