To resist something is to keep it at bay or to fend off its influence or advance. You might not be able to resist the temptation to sneak out to the dance in spite of your parents' objections.
The verb resist comes from the Latin word resistere, meaning “to take a stand,” or “withstand.” People who are able to put up a wall — be it mental, physical, philosophical, emotional, or otherwise — to defend themselves or their group against a threat can be said to resist. The Amish community is still able to resist the influence of technology. Many a child will resist the suggestion to use a napkin. You might resist a second helping of pie.