This is the 844th most frequent German word.
wachsen
To grow.
Here, 'wächst' is the verb form of 'wachsen', used in its literal sense meaning to grow or increase in size.
Der Baum wächst schnell.
The tree grows quickly.
In this sentence, 'aufgewachsen' is employed in its figurative sense, signifying the process of maturing or spending one's childhood years.
Er ist in einer kleinen Stadt aufgewachsen.
He grew up in a small town.
Here, 'wachsen' metaphorically represents improvement or enhancement of abilities.