Question

why is it advisable to breath from our nose and not for our mouth

Answer 1

It is because our nose contains mucus and hair to trap the dust and germ particles, which makes the air we breathe clean but our mouth does not have any of the things which can make inhaled air clean. Therefore, it is advisable to breath from our nose and not for our mouth.

Answer 2

There are some nose hair present in the nostrils which helps in protecting from inhaling pathogens that is germs. It acts like purifying filter. But this couldn't happen in mouth. So it's advisable to breathe through nose rather by mouth.
Thanks!