A second may be one-sixtieth of a minute or the item after first. If you ask whether you're second in line, the hostess might reply, "Give me a second and I'll tell you."
Different meanings of the word second have evolved from the same background, which is the Latin word secundus, which means "next" or "following." Many of the meanings of second follow that idea of a linear "next," including "second base" (comes after "first base"). Back when duels were commonly fought, each dueler chose a second, a friend whose job it was to see that the fight followed the rules. You might have second thoughts about entering a duel, and rightfully so.