Okay, kiddo, imagine that there are two friends named Sarah and John. Sarah really wants candidate A to win the presidential election, but John wants candidate B to win. They both really care about who becomes the next president, but they don't want to cancel each other out by voting for different candidates.
So they come up with a plan called "vote pairing." Sarah agrees to vote for candidate B, even though she wants candidate A to win, and John agrees to vote for candidate A, even though he wants candidate B to win. This way, both of their votes will count towards their preferred candidate and they won't cancel each other out.
This plan only works if Sarah and John both live in states where the race between candidate A and candidate B is really close. If one of them lives in a state where one candidate is way ahead, then their vote won't make much of a difference anyway.
There are websites that help people find a vote pairing partner, so they can make sure that they're not alone in this plan. It's a way for people to still have a say in the election, even if their preferred candidate doesn't have a great shot at winning in their state.
Does that make sense, kiddo?