Hi Su, it depends on the material. If its laminte it can be easily painted. Here's a how to: https://www.uglyducklinghouse.com/i-painted-my-kitchen-countertops/
There are also countertop coatings available that are inexpensive, easy to apply, and extremely durable! Daich makes "stone" coatings and Giani makes "marble" coatings. Both work equally well! I hope this helps!
Mine was a molded laminate. After sanding to give the paint something to stick to I applied several coats of a white latex matte paint. After waiting overnight to let it dry I then applied 2 cans or Rustoleum spray paint with the textured stone look. The next day I followed that with about 5 coats of poly (water based) and let everything dry overnight again. Here is the link I got the basic idea from: