The phrase "huge testament" means something that strongly proves or shows something. It indicates that there is significant evidence or proof supporting a particular idea or statement. Full definition
The coaches actually request to teach at The Little Light House instead of the classes that they get paid for, which is a huge testament to the impact the kids there have on us. (entrepreneur.com)
While being ranked on one of these lists is a huge testament to the employee and leadership team's hard work, it's also a good way for sales teams to narrow down their prospect list. (mattermark.com)
That's a huge testament to the respect they had for our company and the confidence they had in us.» (fooddrink-magazine.com)