I am made of 5 letters

Smile is the 2nd best thing
you can do with your Lips.
What is first thing? ..??..
Teacher: zameen per rehny waly janwer bachy dety hain,
hawa main urnay waly andy daitay hain,

Woh konsi cheez hai jo hawa mai bhi
urti hai or bachy bhi deti hai??
I am made of 5 letters,
If U remove the first letter,
It is part of our body.

If U remove the second letter,
It is everywhere!

Guess what ?