I really like Nice Nature in the game and this picture references an event in her training story, so for context:

Nice Nature the IRL horse was known as the "bronze collector" because it got a lot of 3rd place results in G1 races (sadly it never won a G1 race in its racing career). This translates to the girl Nice Nature in the game to have a sort of defeatist attitude since she always gets 3rd place in major races (it's even part of her unique Skill, she gets a speed boost if she's in 3rd place near the end of a race), but with the help of the trainer she realizes that she really wants to change that and actually win her races. She always refers to herself as a "mob" character compared to the "main characters" like Tokai Teio, but she really wants to shine as a "main character."

In the training mode, after a major race, no matter if she wins or not, the trainer will give her a paper charm they made as a present to cheer her on, and they continue to do so after pretty much every major race. Nice Nature appreciates these presents as they are the symbol of an important person (her trainer) cheering her on to achieve her goals.

So the picture here is referencing her feelings after getting a victory and then getting the paper charm present from her trainer as well.