Question

why does poet (pablo neruda) in his poem keeping quite , that he will count up to twelve and will leave ?

Answer 1

Because 12 seconds are enough for self introspection

Answer 2

He says count upto 12 (in the starting of the poem), he says so because 12 is a number which is universally accepted for eg. there are 12 hrs in a clock, 12 months in a year,etc...

Moreover, when the clock strikes 12, both the hour hand and minute hand meet at this point.

At the end of the poem he is urging us to keep quiet and introspect ourselves and look into universal brotherhood so there will be peace and harmony.