there

The spelling there is used for two words with completely different pronunciations and uses.
adverb of place
There
(pronounced /Qea(r)/) is an adverb meaning ‘in that place’.
What’s that green thing over there?
There’s the book I was looking for.
For the difference between here and there, see here and there.
introductory subject
There
(most often pronounced /Qa(r)/) is used as an introductory subject in sentences beginning there is, there are, there might be etc. For details, see there is. There’s a book under the piano.
there
• and here see here and there
• + inversion (verb before subject) see allow, permit and let.5 , see inversion 2: whole verb before subject
there
• two pronunciations and meanings see there