The phrase "big advance" refers to a significant or substantial progress or improvement in something. It usually implies that there has been a noteworthy leap forward in terms of accomplishment, development, or breakthrough. Full definition
She's making big advances in both gross motor skills (use of the limbs and body) and fine motor skills (use of the hands). (enfamil.com)
It's no longer the world of big advances and national book tours. (feedspot.com)
A new technique using liquid metals to create integrated circuits that are just atoms thick could lead to the next big advance for electronics. (frogheart.ca)