What is the meaning of intercept or constant in the regression model? how you can interpret it?

Intercept means the value of  response variable when all dependent  variables are zero.Some time your intercept does not have a meaning.  for example your "Y" is age and "X"  persons height. there is no meaning interpreting height zero person.but imaging your "X" variable is temperature of the day  and response "Y"  sales of a ice cream.  then you can interpret in a meaning full way.Hope this helps.Cheers.