can any one help how to flash the 230vac lamp with 555 timer for every 5secs

 

You can us an NE555 to drive a relay, the contacts of which are connected in series with the lamp. Make sure the NE555 circuit is properly isolated from the line (example: use a wall wart such as a phone charger) and be careful about the AC wiring. The transistor and voltage ratings in the circuit below depend upon the relay you select.