She spends so much time here.

"Much" is an adjective modifying "time," meaning "lots of time," or "a lot of time."
"So" is an adverb modifying "much," meaning "very much time."

The implication is "a lot of time", often used with a clause beginning with "that".

She spends so much time here that we should give her a key to the door.

She spends so much money on clothes that I'm surprised she has any left to buy groceries.

He complains so much that you would never believe he actually enjoys his job.

The movie is so long that one can barel

Thanks, Philip, I realize I misinterpreted "definition."