The term "tine" refers to a prong or pointed part of a fork, comb, or other tool or object. It's the individual pointy piece that helps to hold, pick up, or separate things.
Complete seal by pressing firmly with tines of fork. (eatpicks.com)
Lightly brush each corner of puff pastry squares with egg; seal pastries by tightly pinching together opposite corners, then pressing together edges with tines of fork to seal completely. (fishernuts.com)
Press edges to seal and crimp using tines of fork. (easydessert.org)