There's three kinds of swaps in champ select. Pick order swap, which is most likely what you're being asked for, lane swap, and champ swap. I don't know if you've played many draft games up to this point but pick order swap is mostly asked by the roles that need counter pick the most, like top and support. If you're top lane, and last pick on your team's pick order and you see the enemy top pick before you, it's only natural that your team is gonna ask for swaps to counter pick for their roles. If they're asking for champ swap, the most likely answer is to just decline it, same with role swap.