Here are some examples:
* "Fonce, tu peux le faire!" (Go for it, you can do it!)
* "N'hésite pas, fonce!" (Don't hesitate, go ahead!)
* "Je ne suis pas sûr, mais fonce quand même!" (I'm not sure, but go ahead anyway!)
"Fonce" literally translates to "go dark", but it's used in a metaphorical sense to express encouragement and boldness.