The phrase "giant step" means making a big progress or achievement in a significant way. It implies taking a major leap forward or accomplishing something substantial. Full definition
The countries where regulation and supervision were so clearly lacking have taken giant steps forward. (theglobeandmail.com)
In 2017, mainstream medicine has taken giant step towards science backed advice. (drcate.com)
After team members have correctly placed all their numbers / fact cards on the rope in the correct order, each team member takes one giant step toward the finish line. (educationworld.com)