Here is the line.
Here I am.
Why can't we hold the party here?
I'm not going out, I'm going to stay here.
I am not a grammar expert so this is a personal opinion. I think it is a sentence. Consider "Here's Tom" or "Here's the bus". They are sentences. Tom is here; the bus is here. Here's why means 'why is here', or 'this [here] is the reason [why]. It is not a particularly good sentence mind you, but it is a sentence.
This here is a sentence with 'get' in it.
Here is your order confirmation for your recent purchase.
You can sit here. What is the naming part of the sentance?
No, "here's why" is typically the beginning of a sentence or phrase that is used to introduce a reason or explanation for something. It is not a complete sentence on its own.
Here is a sentence with the word kilogram.
Here are your keys.
HERE I am! or When did you get HERE
here i am
you
here is a sentence with coddle
Type your answer here... sentence on clamber